wwlmmm^m 


^!€ 


U2A1 


^»ii 


-*  V 


^:a 


r 


M2t1 


;^_^5-^A^^ 


--^■}i-.:U^trt-t. 


'■C^L^ 


A  WORK 

L- — 


ON 


OPERATIVE  DENTISTRY 


IN    TWO    VOLUMES. 


VOLUME   ONE, 
THE  PATHOLOGY  OF  THE  HARD  TISSUES  OF  THE  TEETH. 


GLOSSARY  AND  INDEX. 


187   ILLUSTRATIONS. 


G.  V.  BLACK,  M.D.,  D.D.S.,  Sc.D.,  LL.D. 

nBAN    AND    PROFESSOR   OF   OPERATIVE    DENTISTRY,   DENTAL    P.ATHOLOGT    AND    BACTERIOLOGY 
NORTHWESTERN   UNIVERSITY    DENTAL   SCHOOL. 


SECOND     EDITION. 


CHICAGO: 

MEDICO-DENTAL    PUBLISHING    COMPANY. 

LONDON: 
CLAUDIUS    ASH,    SONS    &    CO..    LTD. 

1914. 


Entered,  according  to  Act  of  Congress,  in  the  year  1911, 

by  G.  V.  Black, 

In  the  Office  of  the  Librarian  of  Congress,  Washington,  D.  C. 


Entered  at  Stationers'  Hall, 
London,  Eng. 


THE    HENRY    O.    SHEPARD   CO.,    PRINTERS,    CHICAGO. 


sol 


PREFACE. 

Tlie  orif?iiial  intention  in  writing'  this  book  was  to  confine  it  strictly  to 
a  consideration  of  dental  caries  and  its  treatment,  but  later  atrophy  and 
erosion  of  the  teeth  were  added.  Atrophy  of  the  teeth  seems  now  U)  have 
been  completely  made  out  both  as  to  its  causation  and  the  principal 
forms  of  the  injury  to  the  hard  tissues  of  the  teeth,  and  it  was  thoufiht 
best  to  place  this  information  on  record  in  permanent  form.  Much  of  the 
detail  as  to  these  in.iuries  may,  however,  be  discovered  in  the  future. 
Our  information  regarding  erosion  is  far  from  complete  and  it  now 
seems  probable  that  much  time  may  elapse  before  its  investigation  will 
develop  satisfactory  results.  Its  apparent  increase  in  frequency  and  the 
great  damage  it  is  doing,  calls  for  the  closest  study  that  the  profession 
can  give. 

Otherwise  than  the  presentation  of  these  two  conditions,  this  book 
will  be  confined  strictly  to  the  consideration  of  dental  caries  and  its 
treatment.  This  comprises  the  main  features  of  Operative  Dentistry, 
though  in  fact  it  is  only  one  department  of  oi:r  daily  work  at  the  chair. 
Diseases  of  the  dental  pulp,  diseases  of  the  peridental  membranes, 
alveolar  abscess,  and  the  whole  group  of  pathological  conditions  of  the 
soft  tissues,  are  sub,jeets  for  another  volume.  The  time  has  passed  for 
including  in  one  book  all  of  the  subjects  of  dentistry. 

Wliile  I  have  not  been  unmindful  of  the  needs  of  the  general  prac- 
titioner in  the  preparation  of  the  book,  it  has  been  planned  especially  for 
use  of  students  in  dental  schools.  The  subjects  are  introduced  and  car- 
ried forward  step  by  step,  from  the  simpler  to  the  more  complex,  wdth 
complete  explanations  of  the  nomenclature  for  the  beginner  in  the  work 
of  preparing  cavities  and  filling  teeth.  In  the  treatment  of  this  sub- 
ject, the  questions  of  the  pathology  of  caries  applicable  to  the  prevention 
of  recurrence  of  decay  after  fillings  have  been  made,  and  the  conditions 
under  which  operations  should  or  should  not  be  done,  have  been  repeated 
often  in  order  to  keep  these  matters  constantly  before  the  mind  of  the 
student. 

In  the  arrangement  of  the  matter,  the  logical  order  usually  observed 
in  books  has  been  followed.  That  is,  the  pathology  has  been  presented 
first  and  the  treatment  later.  This  is  not  always  the  best  order  in  teach- 
ing, and  especially  when  the  subjects  are  presented  in  that  detail  that  is 
necessary  to  completeness.  In  order  to  read  most  understandingly  of 
the  pathology  of  typhoid  fever,  for  instance,  one  must  have  had  much 
practical  observation  of  the  disease.  The  more  prominent  facts  should 
toe  obtained  first  and  the  more  intimate  detail  added  later,  when  per- 
sonal observation  has  given  a  wider  view.  In  the  study  of  dental  caries 
and  its  treatment,  I  have  usually  preferred  to  adopt  such  a  plan  in 
teaching.  With  that  view,  the  second  volume  would  be  given  to  the 
student  first.  Following  this  thought,  an  outline  of  the  principal  points 
of  the  pathology  involved  is  usually  given  with  or  preceding  the  treat- 
ment of  each  class  of  dental  caries.     In  the  first  study  by  which  the 


IV  PATHOLOGY    OF    THE    HAED   TISSUES    OF    THE    TEETH. 

student  is  prepared  for  the  beginning  of  the  practical  observation  and 
treatment  of  caries,  this  answers  the  purpose.  The  more  serious  study 
of  the  pathology  of  dental  caries  is  then  undertaken  later.  If  this  plan 
is  adopted,  the  first  parts  of  the  second  volume  would  be  given  the  stu- 
dent in  the  operative  technic  course  in  the  fresliman  year.  This  would 
be  reviewed  and  completed  in  the  junior  year.  The  first  volume  would 
then  belong  to  the  senior  year.  The  book  may  be  used,  however,  in 
either  order.  In  the  order  as  arranged,  the  more  .serious  study  of  the 
pathology  coming  first,  the  reminders  introduced  in  the  second  volume 
will  be  of  direct  advantage. 

With  but  few  exceptions,  the  illustrations  are  original.  Those  illus- 
trating the  preparation  of  cavities  are  reproductions  of  pictures  made 
by  my  o-ma  brush,  and  the  photographs  and  photomicrographs  have  been 
made  by  Dr.  F.  B.  Noyes  from  specimens  of  my  personal  preparation 
from  material  I  have  gathered  myself,  which  remained  under  my  per- 
sonal observation  and  study  during  the  entire  process.  I  am  under 
especial  obligation  to  Dr.  Noyes  for  the  excellent  assistance  he  has  given 
in  the  photographic  work,  and  to  my  son.  Dr.  Arthur  D.  Black,  for  very 
valiiable  assistance  and  .suggestions  in  the  preparation  and  arrangement 
of  the  manuscript. 

G.  V.  BLACK. 
Chicago,  III.,  June  22,  1908. 


PREFACE   TO   SECOND   EDITION. 

The  sale  of  this  work  has  now  exhausted  the  first  edition  of  five 
thousand  copies.  This  happens  to  come  at  a  time  when  I  am  unusually 
busy  in  the  preparation  of  a  work  on  the  pathology  of  the  dental  pulp 
and  the  investing  tissues  of  the  teeth,  and,  as  I  do  not  feel  that  a  revision 
of  this  work  is  necessary  at  the  present  time,  I  publish  a  second  edition 
with  the  correction  of  a  few  errors  and  omissions. 

G.  V.  BLACK. 

Chicago,  Augxist  3,  1914. 


CONTENTS   OF   VOLUME    I. 


PATHOLOGY  OF  THE  HARD  TISSUES  OF  THE  TEETH. 


PAGE 

Introduction   1 

Atrophy  op  the  Teeth 6 

Etiology    11 

Histological  Characters  in  Atrophy  of  the  Teeth 14 

Atrophy  of  the  First  Permanent  Molare 23 

Treatment  of  Atrophied  Teeth 25 

Pits  in  the  Enamel 30 

Other  Deformities  of  the  Enamel 32 

General  Deformity  of   Enamel 32 

White  Spots  in  the  Enamel 34 

White  Enamel   35 

Erosion  op  the  Teeth 39 

Diagnosis  of  Erosion 40 

Frequence   of   Erosion 41 

Forms  of  Erosion 42 

Etiology  of  Erosion 49 

Treatment   of   Erosion 57 

Caries  op  the  Teeth 60 

Historical    60 

General  Statement   65 

Caries  op  Dentin 68 

Caries  op  Enamel 74 

Penetration  of  Enamel  in  Pits 76 

Penetration  of  Enamel  in  Proximal  Surfaces  of  Incisors 77 

Superficial  Spreading  of  Caries  in  Proximal  Surfaces  of  Bicus- 
pids and  Molars 81 

A  Closer  Examination  of  the  Injury  to  the  Enamel 83 

The  Relation  of  Occlasion  to  the  Localization  of  Caries 85 

Penetration  of  Enamel  in  Buccal  and  Labial  Surfaces 90 


VI  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

PAGE 

Caries  as  a  Whole.     Its  Clinical  Features 91 

Occlusal  Surface  Decays  in  Molars 92 

Proximal  Surface  Decays  in  Molars 93 

Occlusal  and  Proximal  Surface  Decays  in  Bicuspids 97 

Misplacement  of  Beginning  Proximal  Decays 100 

Secondary  Extensions  Gingivally  of  Proximal  Decays 101 

Injuries  by  Interproximal  Wear 104 

Proximal  Surface  Decays  in  Incisors  and  Cuspids 107 

Gingival  Third  Decays  in  Labial  and  Buccal  Surfaces 109 

Spreading  of  Decay  Around  the  Teeth 113 

Systemic  Conditions 115 

Physical  Characters  of  the   Teeth 118 

General  Summary  of  Results  of  Physical  Examinations  of  the 

Teeth    120 

The  Hardness  and  Softness  of  the  Teeth 122 

Faults  in  the  Structure  of  the  Enamel 124 

Physiological  and  Pathological  Differences  between  Bone  and 

Dentin    126 

Studies  by  Dr.  J.  Leon  Williams 128 

Sialo-semeiology    129 

The  Saliva 132 

Acidity  of  the  Saliva,  Viscosity  of  the  Saliva,  Glutinous 
Deposits  from  the  Saliva,  Signs  of  Susceptibility  and 
Immunity  to  Dental  Caries. 
Microorganisms  of  the  Mouth 138 

Utility  of  Studies  of  Dental  Caries 142 

Vital  Phenomena  in  Caries 144 

Sensation  in  Dentin 146 

Obtunding  Sensitive  Dentin 148 

Thermal  Sensitiveness   150 

Management  op  Patients 153 

Cleanliness    154 

Cleaning  which  Patients  should  do  for  Themselves,  The 
Tooth  Brush,  Mouth  Washes,  Tooth  Powders,  The 
Toothpick,  Ligature,  Tape  and  Rubber  Bands. 


TABLE    ()!•'    CONTENTS.  VII 

PAGE 

The  Force  Used  in  Mastication  in  Relation  to  the  Strength  and 

Health  op  the  Peridental  Membrane 161 

The  Force  Used  in  Chewing  Foods 161 

Gnathodynamometer  Records. 

The  Force  Required  in  the  Mastication  of  Food 165 

Phagodynamometer  Records. 

Sensitiveness  of  the  Peridental  Membrane 168 

Management  op  Light  and  Care  op  the  Eyes 172 

Examinations  of  the  Mouth 178 

Treatment  op  Dental   Caries 188 

Prophyhictic  Treatment  of  Caries  by  Artificial  Cleaning 188 

Treatment  of  Dental  Caries  by  Filling 190 

Curative   Effect   of   Fillings 193 

Selection  of  Filling  Material 198 

Management  op  Cavities  by  Classes 203 

Classification    203 

Cavities  of  the  First  Class 204 

Cavities  of  the  Second,  Third  and  Fourth  Classes 208 

Limitation  of  Extension  for  Prevention 214 

Thermal  Sensitiveness   219 

Lodgments  of  Food  in  the  Interproximal  Space 220 

Prophylactic  Value  of  Form  in  Proximal  Fillings 222 

Cavities  of  the  Fifth  Class 225 

Caries  in  Cases  of  Recession  of  the  Gums 230 

Esthetic  Considerations 232 

Management  op  CkhjOren's  Teeth 235 

Relation  of  Growth  and  Shedding  of  the  Decidiious  Teeth  to 

their  Treatment    237 

Premature  Eruptions  of  Teeth 238 

Absorption  of  the  Roots  of  the  Deciduous  Teeth 239 

Accidents  During  Absorption  of  Roots  of  the  Deciduous  Teeth  241 

Treatment  of  Caries  of  the  Deciduous  Teeth 247 

Treatment  of  Decays  of  the  Deciduous  Incisors  and  Cuspids.  .  .   248 
Treatment  of  Decaj's  in  the  Deciduous  Molars 253 


VIII  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

PAGE 

The  Childhood  Period  of  the  Permanent  Teeth 258 

Growth  of  the  Roots  of  the  Permanent  Teeth 258 

Intereusping  of  the  First  Permanent  Molars 262 

Special  Functions  of  the  First  Permanent  Molars 263 

Caries  of  Permanent  Teeth  During  the  Childhood  Period 265 

First  Pennanent  Molars,  Lingual  Pits  of  Lateral  Incisors, 
Proximal  Cavities  in  the  Incisor  Teeth,  Proximal  Sur- 
face Decays  of  Lateral  Incisors,  Open  Apical  Ends  of 
Root  Canals,  The  Pulps  of  the  Lateral  Incisors. 

Glossary 279 

Index 307 


LIST    OF    ILLUSTRATIONS. 


NUMBER 

Atrophy  op  the  Teeth 1-47 

Incisors  and  cuspids 1,  2,  3,  4,  5,  6,  7,  8,  18,  19,  26 

Diagram  showing  positions  of  atrophy  marks  at  various  ages. .       9 

Diagram  showing  lines  of  Ritzeus 10 

Sections  of  incisors  and  cuspids  showing  zones  of  atrophy.  .11, 

12,  13,  14,  15,  16,  20,  23,  24,  25,  27,  28,  29 

Diagram  showing  zones  of  atrophy,  Zsigmundy 17 

Zone  of  injury  from  atrophy  mid-length  of  root 21,  22 

Cast  showing  atrophy  of  first  permanent  molar 30 

Sections  of  first  permanent  molars  showing  zones  of  atrophy 

31,  32,  33 

Pits  in  the  enamel 34,  35 

General  deformity  of  the  enamel 36,  37,  38,  39,  40,  41,  42,  43 

White  enamel  44,  45 

White  spots  in  the  enamel 46,  47 

Erosion  of  the  Teeth 48-62 

Dish-shaped  areas   48,  49,  61 

Wedge-shaped  areas   50,  51,  52 

Flattened  areas 53,   54,  55 

Irregular  areas  56 

Figured  areas   57,  58,  59,  60 

Gold  crown  cut  by  erosion 61 

Proximal  surface  erosion 62 

Caries  of  the   Teeth 63-145 

Caries  of  Dentin 63-74 

Dializer    63,  64 

Salts  dialized  from  saliva -t.     65 

Crystals  of  sugar 66 

Tooth  split  to  show  area  of  decay 67 

Occlusal  surfaces  of  molars 68,  69,  70 

Split  teeth   71,  72 

Dentinal  tubules  containing  microorganisms 73,  74 


X  PATHOLOGY    OF    THE    HAKD   TISSUES    OF    THE    TEETH. 

NUMBER 

Caries  of  Enamel 75-103 

Occlusal  surfaces,  pit  decays,  split  teeth 75,  76,  77 

Proximal  surface  decays  in  incisors: 

Proximal  surface   78 

Split  teeth    79,  80,  81 

Photomicrographs  of  sections ■. .  .  82,  83,  84,  85 

Proximal  surface  decays  in  bicuspids  and  molars : 

Proximal  surfaces 86,  87,  88,  89,  90,  91 

Cross   cuts    92,  93,  94,  95 

Photomicrographs  of  sections  showing  the  injury  to  the  enamel 

by  caries    96,  97,  98 

Relation  of  occlusion  to  the  localization  of  caries: 

Buccal  view  of  bicuspids  and  molars 99 

Occlusal  view  of  bicuspids  and  molars 100 

Normal   occlusion,   buccal  view 101 

Occlusal  views  of  upper  and  lower  teeth 102,  103 

Caries  as  a  Whole.    Its  Clinical  Features 104-145 

Occlusal  surface  decays  in  molars,  split  teeth 104,  105,  106 

Proximal  surface  decays  in  molars,  split  teeth..  107,  108,  109, 

110,  111 
Occlusal  and  proximal  surface  decays  in  bicuspids: 

Split  teeth  112,  113,  114,  117,  118 

Photomicrographs  of  sections 115,  116 

Misplacement  of  beginning  decays,  central  incisor 119,  120 

Secondary  extensions  gingivally  of  proximal  decays,  photomi- 
crographs of  sections 121,  122,  123 

Injuries  by  interproximal  wear 124,  125,  126,  127,  128 

Proximal  surface  decays  in  incisors  and  cuspids : 

Proximal  surfaces    129,  130 

Split  teeth  131,  132,  133 

Gingival  third  decays  of  buccal  and  labial  surfaces.  .134,  135, 

136,  137,  138,  139,  140,  141 
Spreading  of  decay  around  the  teeth 142,  143,  144,  145 

Systemic  Conditions  146-158 

Physical  characters  of  the  teeth,  photomicrographs  of  .sections 

of  enamel 146,  147,  148,  149,  150 

Physiological  and  pathological  differences  between  bone  and 
dentin,  photomicrographs: 

Cross  section  of  bone 151 

Lengthwise  section  of  bone 152 

Cross  section  of  root  of  tooth  showing  absorption 153 


LIST    OF    ILLUSTRATION S.  XI 

NUMBER 

Section  of  bone,  showing  absorption 154 

Section  of  root  of  tooth,  showing  repair  of  absorption  by 

cementum    155 

Plaques  on  the  teeth,  photomicrographs  of  sections  of  teeth  and 

plaques.     Williams  156,  157,  158 

Vital  Phenomena  in  Caries 159-161 

Diagram  illustrating  sensation  without  nerves  in  dentin 159 

Split  incisors,  showing  abrasion 160,  161 

Force  of  Mastication 162-166 

Gnathodynamometer,  for  measuring  strength  of  bite 162,  163 

Dynamometer,  with  micrometer  attachment  for  determining 
stress  a  substance  will  bear  without  crushing,  also  the  com- 
pression under  stress  164,  165 

Phagodynamometer,  for  measuring  force  required  to  chew  food .   166 

Treatment  of  Dental  Caries  by  Filling,  Photomicrograph  of 
Salts  Dialized  from  Saliva 167 

Caries  in  Cases  of  Recession  of  the  Gums,  Treatment  by  Silver 
Nitrate    168,  169,  170,  171 

Management  of  Children's  Teeth 172-186 

Diagram  showing  calcification  of  the  deciduous  teeth 172 

Diagram  showing  absorption  of  the  roots  of  the  deciduous  teeth  173 
Apex  of  root  of  deciduous  incisor  forced  through  gum  by  per- 
manent tooth    174,  175,  176 

Treatment  of  caries  of  the  deciduous  teeth : 

Labial  view  of  deciduous  incisors 177 

Lingaial  view  of  deciduous  incisors 178 

Proximal  decays  of  deciduous  incisors  treated  by  filing  and 

silver  nitrate   179,  180,  181,  182 

Proximal  decays  of  deciduous  molars  treated  by  cutting 

and  silver  nitrate 183,  184,  185,  186 

Childhood  Period  of  the  Permanent  Teeth. 

Diagram  showing  calcification,  period  of  eruption,  and  time  of 

completion  of  roots  of  the  permanent  teeth 187 


Pathology  of  the  Hard  Tissues  of  the  Teeth. 


INTRODUCTION. 

THE  injuries  which  occur  to  the  hard  tissues  of  the  teeth  dur- 
ing their  development,  and  which  occur  to  them  by  accident 
or  disease  after  they  have  grown,  are  peculiar  to  the  enamel  and 
dentin.  They  have  no  apparent  relation  or  natural  kinship  ^ith 
similar  developmental  or  acquired  injuries  or  diseases  of  other 
tissues  of  the  body,  except  some  atrophic  injuries  to  the  hair  and 
nails.  This  is  made  so  by  the  histological  structure  of  those 
tissues,  in  that  they  have  no  power  of  repair  and  recovery  from 
injuries.  The  hair,  nails,  and  the  continuous  growing  teeth  of 
a  few  animals,  while  having  no  means  of  repair  of  developmental 
or  acquired  injuries,  dispose  of  the  injured  parts  by  the  pro- 
vision for  the  wearing  away  of  the  substance,  and  with  this  the 
defects.  Growth  continues  to  supply  new  material,  and  in  this 
negative  way  may  effect  a  repair. 

The  soft  tissue  appendages  of  the  teeth,  however,  as  the 
pulps,  peridental  membranes,  alveolar  processes,  gums,  etc.,  are 
developed  under  similar  histological,  physiological  and  patho- 
logical laws  as  other  soft  tissues  and  bones;  and  possess  similar 
powers  of  repair. 

The  developmental  injuries  are  confined  to  failure  in  develop- 
ment of  parts  of  the  enamel  and  dentin  because  of  general  sys- 
temic conditions  which  interfere  with  nutrition  at  a  time  when 
some  particular  part  of  the  tooth  is  being  formed,  or  is  growing, 
and  the  injury  is  confined  to  that  part.  Other  tissues  have  the 
power  of  repair  of  such  injuries  later.  Since  the  enamel  and 
dentin  do  not  have  this  power  of  self-repair,  such  injuries  in 
them  are  permanent.  There  is  a  similar  failure  of  self-repair 
in  these  tissues  when  injured  by  accident  or  disease  after  they 
have  been  formed,  or  have  grown  and  completed  their  develop- 
ment, such  as  accidental  breakage  of  parts  or  injuries  by  erosion 
or  by  caries.    As  these  tissues  are  not  subject  to  inflammation, 

1 


2  PATHOLOGY   OF    THE    HABD    TISSUES    OF    THE    TEETH. 

nor  to  physiological  or  pathological  changes  in  the  same  sense 
Lq  which  these  occur  in  soft  tissues  and  the  bones,  and  as  they 
are  amenable  to  treatment  only  by  artificial  repair,  it  seems 
especially  fit  and  desirable  that  these  be  considered  in  a  group 
to  themselves. 

Those  conditions  that  occur  in  the  form  of  malformations  or 
misbuildings,  such  as  supernumerary  teeth,  odontomes,  mal- 
formed teeth,  etc.,  belong  to  a  different  class  and  require  totally 
different  treatment. 

Atrophy  of  the  teeth  is  met  with  so  frequently  in  the  practice 
of  operative  dentistxy,  and  the  injuries  of  the  teeth  are  often  so 
severe,  that  it  has  seemed  to  me  that  the  facts  gathered  by  recent 
investigations  should  be  placed  in  permanent  form  in  our  litera- 
ture. Until  very  recently  little  had  been  accurately  known  of 
the  forms  of  these  lesions,  and  many  errors  are  being  made  in 
the  treatment  which  may  be  avoided  by  a  closer  study  of  the  con- 
ditions. While  in  many  cases  but  little  can  be  done  to  improve 
the  appearance  of  atrophied  incisors,  a  large  proportion  of  the 
first  molars  which  are  now  lost  may  be  protected  and  remain 
useful  in  mastication,  as  well  as  to  serve  their  full  purpose  in  the 
development  of  the  features. 

On  the  subject  of  erosion,  much  greater  interest  is  being 
manifested  in  recent  years  than  formerly;  the  interest  in  it.^ 
pathology  has  been  increased  by  recent  investigations  and  the 
continuance  of  these  should  be  stimulated  with  the  hope  that  its 
causation  may  become  more  definitely  known  and  some  satis- 
factory cure  or  preventive  discovered. 

The  subject  of  dental  caries  and  its  treatment  is  and  must 
remain  the  most  important  subject  in  conservative  dentistry. 
No  great  improvement  in  its  treatment  can  be  had  without 
improvement  in  the  understanding  of  its  causation,  the  condi- 
tions of  the  beginnings  of  caries  of  the  enamel  and  the  means  to 
be  employed  in  the  prevention  of  its  recurrence  about  the  mar- 
gins of  fillings.  To  this  end,  extensive  studies  have  been  made 
of  this  particular  phase  of  the  subject  with  the  view  of  placing 
that  which  is  now  known  in  systematized,  usable  form,  for  both 
students  in  dental  schools  and  for  practitioners.  This  feature 
of  operative  dentistry  has  been  deemed  of  so  much  importance 
to  the  dental  profession  and  to  our  people  tliat,  in  writing  of 
technical  procedures  in  filling  teeth,  it  has  been  held  continuously 
before  the  mind  of  the  student  and  practitioner  by  frequent 
explanations  and  repetitions.  This  has  seemed  necessary  because 
of  the  general  disregard  of  the  study  of  dental  caries  in  its  rela- 


INTBODUCTION.  3 

tion  to  treatment  by  filling  shown  by  most  recent  writers.  It  is 
intrinsically  wrong  to  treat  the  subject  of  filling  teeth  simply 
from  the  mechanical  standpoint;  it  is  wrong  in  that  it  tends  to 
produce  in  the  minds  of  students  the  idea  that  filling  teeth  is  a 
purely  mechanical  pursuit.  This  is  far  from  the  proper  concep- 
tion of  the  facts.  In  fiUing  teeth,  the  closest  use  of  our  knowl- 
edge of  the  pathology  of  dental  caries  and  of  the  local  conditions 
of  its  occurrence,  and  of  its  recurrence  after  fillings  have  been 
made,  should  be  put  to  full  use  in  every  case,  in  order  that  the 
greatest  benefit  may  be  derived  from  filling  operations.  To  state 
this  in  the  fullest  detail  has  been  a  special  object. 

To  this  end,  studies  have  been  made  of  dental  caries  and  the 
various  forms  it  assumes  in  its  beginnings  in  the  enamel,  spread- 
ing of  colonies  of  microorganisms  on  the  surface  of  the  enamel, 
carrying  with  them  the  spreading  of  beginnings  of  caries  into 
the  surface  of  the  enamel,  and  the  manner  of  penetration  of  the 
enamel.  These  have  been  carefully  illustrated  by  photographs 
and  photomicrographs,  beginning  with  the  simplest  forms,  and, 
by  careful  arrangement,  proceeding  to  the  more  complex  through 
the  different  phases.  There  have  been  included,  so  far  as  seemed 
possible  by  this  method,  illustrations  of  the  directions  of  this 
spreading  and  the  local  conditions  which  favor  it  and  which 
hinder  or  prevent  it.  The  areas  of  the  surfaces  of  the  teeth  rela- 
tively most  susceptible  to  the  beginnings  of  caries,  as  differen- 
tiated from  the  immune  or  relatively  immune  areas,  have  also 
been  illustrated.  On  account  of  the  extreme  importance  in  the 
practical  operations  of  filling  teeth  of  this  particular  phase  of 
the  subject,  it  has  been  illustrated,  with  two  or  three  exceptions 
only,  by  photographs  and  photomicrographs  reproduced  by  the 
half-tone  method  without  any  retouching  or  artificial  modifica- 
tion in  any  way.  To  these  a  few  diagrammatic  illustrations  have 
been  added. 

The  fact  has  been  kept  prominent  that  immunity  to  dental 
caries,  which  may  be  complete,  or  which  will  approach  complete- 
ness, even  in  persons,  who,  as  children,  were  very  susceptible  to 
caries,  will  become  established  in  early  adult  life  in  the  larger 
proportion  of  cases  in  which  effective  protection  has  been  given 
by  filling  operations,  by  continuance  of  active  mastication  of 
food,  and  reasonable  care  as  to  cleanliness.  This  matter,  which 
was  neglected  because  of  previous  misinterpretation  of  observed 
facts,  is,  with  continued  observation,  assuming  greater  impor- 
tance in  dental  practice.  The  systemic  conditions  producing  the 
changes  in  the  saliva  on  which  susceptibility  and  immunity  are 


4  PATHOLOGY    OF    THE    HABD    TISSUES    OF    THE   TEETH. 

based,  while  making  progress,  has  not  yet  assumed  any  such 
exactness  of  definition  as  to  be  of  immediate  use  in  practice. 

In  the  technical  procedures  in  filling  teeth,  the  details  of  the 
adaptation  of  instruments  to  the  work  of  cavity  preparation 
have  been  brought  into  close  systematization  through  notes  of 
practical  work  at  the  chair  representing  actual  operative  experi- 
ence. This  has  been  expressed  in  forms  of  nomenclature  that  are 
simple,  systematic  and  effective  in  teaching,  in  pointing  out  defi- 
nitely the  instruments  for  use  and  the  manner  of  use  of  each. 
Every  detail  of  cavity  form  is  systematized  and  brought  under 
a  system  of  nomenclature  comprised  under  a  very  few  efficient 
rules,  which  render  it  simple  and  effective  for  teaching  purposes 
and  for  general  use  by  practitioners  of  dentistrj\  All  of  this  has 
been  systematized  and  improved  through  many  years  of  actual 
work  in  teaching  and  has  proven  sufficiently  flexible  to  cover  all 
kinds  and  varieties  of  cases  presented.  The  careful  classifica- 
tion of  cavities  and  of  instrument  forms  adapted  to  each  make  it 
possible  to  teach  cavity  preparation  in  a  way  that  it  is  easily 
learned;  cavities  may  be  more  easily  prepared,  the  time  con- 
sumed is  shortened,  the  operation  is  more  definite  in  its  results. 
Taken  altogether,  these  mark  an  improvement  in  the  effective- 
ness of  operative  dentistry. 

Improvements  that  seem  to  have  been  but  little  thought  of 
heretofore  have  been  made  subjects  of  careful  study  and  system- 
atization. Operative  dentistry,  particularly  when  closely  pursued 
for  years  together,  is  extremely  taxing  upon  the  nervous  system 
of  the  operator,  and  many  men  break  themselves  down  purely 
through  assuming  positions  at  the  chair  that  are  unnecessarily 
fatiguing.  This  arises  from  assuming  wrong  positions  in  the 
beginning  and  the  failure  to  obtain  that  relief  which  is  clearly 
and  easily  possible  by  change  and  the  rest  that  change  brings, 
without  ceasing  or  slowing  the  work  at  the  chair.  Systematization 
of  these  matters  and  bringing  them  under  forms  of  nomenclature 
in  which  they  may  be  taught  and  discussed  understandingly 
should  result  in  great  good. 

Dentistry  has  its  own  nomenclature  which  has  become  dis- 
tinct from  the  nomenclature  of  comparative  dental  anatomy. 
The  nomenclature  of  dental  anatomy  from  the  standpoint  of 
dentistry  and  of  operative  dentistry  belongs  distinctively  to 
dentistry,  and  should  in  no  case  be  confounded  with  the  nomen- 
clature of  comparative  dental  anatomy,  nor  the  one  used  in  the 
place  of  the  other,  nor  should  any  effort  be  made  to  harmonize 
them.    When  the  human  teeth  are  under  consideration  from  the 


INTRODUCTION.  5 

comparative  anatomy  standpoint,  the  nomenclature  of  compara- 
tive anatomy,  which  is  suited  to  the  description  of  the  teeth  of 
animals  in  general,  should  be  used.  In  that  nomenclature  we  do 
not  speak  of  buccal  and  lingual  surfaces  of  teeth  but  of  inner 
and  outer  sui-faces,  the  bicuspids  in  dental  nomenclature  become 
premolars  in  comparative  dental  anatomy.  While  there  are 
points  of  coincidence  in  these  nomenclatures,  there  are  wide 
differences  that  could  not  be  reconciled  without  positive  injury 
to  both. 


PATHOLOGY    OP    THE    HABD   TISSUES   OF    THE   TEETH. 


ATROPHY  OF  THE  TEETH. 

ILLUSTRATIONS:    FIGURES  1-47. 

THE  term  "atrophy"  includes  two  distinct  ideas;  the  one  is 
a  failure  of  the  development  of  a  local  part  because  of  a  fail- 
ure of  nutrition,  the  other  is  a  wasting  of  a  part  because  of  a  local 
failure  in  the  nutritive  processes.  Atrophied  teeth  belong  to 
the  first  class ;  they  have  never  been  fully  formed.  They  come 
through  the  gums  in  the  condition  of  deformity  in  which  they 
are  afterward  seen,  and  do  not,  as  some  seem  to  suppose,  waste 
away  after  having  taken  their  places  in  the  arch.  The  deformity 
is  a  result  of  incomplete  formation.  The  term  "hypoplasia" 
has  of  late  been  widely  used  in  the  German  language  in  the  same 
sense  and  is  being  adopted  by  some  writers  in  English.  The 
author  has  preferred  to  use  the  older  term  which  has  been  used 
to  designate  this  condition  since  it  was  first  spoken  of  in  the 
English  language. 

In  the  human  teeth  there  is  no  process  of  repair  and  the 
deformity  is  permanent.  Similar  phenomena  occur  in  the  finger 
nails  and  the  hair.  During  an  illness  that  interferes  seriously 
with  nutrition,  the  portion  of  the  finger  nail  then  forming  will 
be  dwarfed,  which  will  appear  later  as  a  groove  across  the  nail. 
This,  like  the  marking  of  the  teeth,  is  not  remedied  by  any  repar- 
ative process.  But  the  nail  is  continuously  growing  and  the 
groove  moves  on  over  the  length  of  the  nail  and  disappears. 

During  a  severe  illness  that  interferes  with  nutrition,  a  sec- 
tion of  hair  is  imperfectly  formed,  and  when  in  the  process  of 
growth  this  section  arrives  at  the  surface  of  the  skin  and  is  sub- 
jected to  bending,  it  breaks  and  the  hair  suddenly  falls  away 
These  are  conmion  phenomena  following  severe  cases  of  typhoid 
fever.  The  hair  follicles  are  not  injured  and  the  hair  is  replaced 
by  the  regular  process  of  growth. 

In  the  continuously  growing  teeth  of  the  rodents  such  an 
injuiy  would  be  finally  removed  and  remedied  in  the  same  way 
as  the  grooving  seen  upon  the  finger  nails,  but  this  can  not  occur 
in  the  human  teeth. 

The  deformity,  though  much  varied  in  different  cases,  is, 
when  closely  analyzed,  always  similar  in  character.    It  always 


Fia.   1. 


lAAAiy 


Fia.  2. 


iteAAiljp 


Fia.  3. 


Fig.  4. 


FiQ.  1.  Atrophy  of  the  cutting  edge  of  the  central  incisors,  forming  a  central  notch  or  scar. 
This  is  usually  called  "  Hutchinson's  tooth."  In  connection  with  this  form  of  atrophy,  the  occlusal 
surfaces  of  the  first  molars  are  also  badly  marked. 

Fig.  2.  Atrophy  of  the  cutting*  edge  of  the  central  and  lateral  incisors.  When  this  occurs,  some 
portions  of  the  occlusal  surfaces  of  the  first  molars  will  also  be  injured. 

Fig.  3.  Atrophy  marks  on  the  incisors  and  cuspids.  In  this  case  there  is  a  pitted  groove  around 
the  crown  of  each  tooth  atrophied.     The  first  molars  have  a  similar  groove  on  their  axial  surfaces. 

Fig.  4.     Atrophy  marks  on  the  incisors,  showing  the  inverted  fingernail  scar  on  the  lateral  incisors. 


Fia.  5. 


Fia.  6. 


Fro.  7. 


Figs.  5,  6  and  7.  Single  teeth,  the  crowns  of  which  have  been  badly  dwarfed  by  atrophy.  Each 
of  these  show  two  zones  of  injury.  The  dotted  lines  are  intended  to  show  the  normal  outlines  of  the 
crowns.  Figin-es  5  and  G  are  different  views  of  the  same  tooth. 


ATROPHY    OF    THE    TEETH.  7 

consists  in  a  failure  of  the  formation  or  an  imperfect  formation 
of  some  specific  portion  of  the  tooth  and  of  several  teeth  together. 
The  portion  of  the  several  teeth  affected  is  always  that  portion 
of  each  that  was  in  process  of  formation  or  growth  at  the  same 
period  in  the  person's  existence.  To  understand  this  well  one 
should  study  closely  the  calcification  of  the  crowns  of  the  teeth 
and  the  contemporaneous  lines  of  calcification  of  the  different 
teeth.  This  will  be  more  fully  explained  in  considering  the  histo- 
logical changes  occurring  in  atrophy.  In  the  incisors  the  de- 
formity is  oftenest  seen  in  the  form  of  a  groove,  smooth  or  pitted, 
rimning  across  the  labial  surface  from  mesial  to  distal,  and  close 
inspection  will  generally  show  that  it  encircles  the  tooth  com- 
pletely, though  it  is  most  prominent  upon  the  labial  surfaces 
where  the  enamel  is  thickest.  It  is  seen  more  often  on  the  incisal 
half  of  the  length  of  the  crown.  It  may  be  near  the  cutting  edge 
of  the  tooth  or  anywhere  from  that  point  toward  the  gingival 
line.  It  is  also  found  occasionally  in  the  roots  of  extracted  teeth. 
There  may  be  a  single  groove  or  pitted  line,  or  there  may  be  two 
or  even  three  or  more  of  these.  The  teeth  affected  are  the  inci- 
sors, cuspids  and  first  molars  of  the  permanent  set,  and  very 
rarely  the  first  bicuspids.  If  it  is  very  close  to  the  cutting  edge 
on  the  central  incisors  it  may  not  appear  on  the  laterals,  but  the 
occlusal  surfaces  of  the  first  molars  will  be  atrophied.  This  is 
because  these  parts  of  these  teeth  are  in  process  of  formation 
at  the  same  time.  If  the  groove  is  a  little  further  removed  from 
the  incisal  edge  of  the  centrals,  the  lateral  incisors  will  also  be 
similarly  affected.  If  it  is  a  little  higher  still,  the  four  incisors, 
upper  and  lower,  the  cuspids  and  the  first  molars  will  be  affected, 
but  the  bicuspids  will  be  free  from  injury.  It  is  exceedingly  rare 
that  the  bicuspids  or  the  second  or  third  molars  are  affected  by 
atrophy,  for  the  reason  that  the  enamel  and  dentin  of  these  teeth 
generally  have  not  begun  to  form  until  after  the  age  at  which 
these  effects  are  most  liable  to  occur.  But  few  cases  occur  in 
which  the  first  bicuspids  are  marked.  The  time  of  the  occurrence 
of  these  injuries  seems  to  be  confined  mostly  to  the  first  five 
years  of  a  child's  life,  but  some  cases  occur  later. 

In  the  engravings  the  endeavor  has  been  to  illustrate  some 
of  the  more  severe  types  of  these  deformities  and  to  explain  by 
illustration  the  histological  defects.  Figure  1  represents  what 
is  known  as  the  typical  Hutchinson  tooth,  from  the  claims  of  Mr. 
Hutchinson,  a  specialist  in  venereal  diseases  in  London,  England, 
who  insisted  that  this  deformity  was  the  result  of  inherited  syph- 
Uis.    In  such  cases,  it  has  formerly  been  supposed  that  the  middle 


8  PATHOLOGY   OF    THE    HAED   TISSUES   OF    THE   TEETH. 

lobe  lias  failed  of  formation,  resulting  in  this  peculiar  scar,  but 
more  recent  investigation  seems  to  show  that  the  whole  incisal 
edge  has  failed  in  most  of  these  cases,  and  that  the  angles  of  the 
tooth  have  been  drawn  together  over  the  injury,  giving  the  out- 
line of  the  tooth  this  rounded  appearance.  Certainly  many  of 
these  teeth  are  much  shorter  than  normal.  Generally  an  ugly 
deformity  of  the  occlusal  surfaces  of  the  first  molars  accompanies 
this  type.  In  the  molars  little  spiculse  of  cusps  are  likely  to  be 
sticking  up  much  too  close  together,  while  the  rest  of  the  occlusal 
surfaces  are  much  too  small,  crumpled  together  and  sunken  into 
the  crown,  which,  other  than  this,  will  be  of  full  size  and  form. 
These  teeth  decay  quickly  in  case  there  is  a  tendency  to  caries  in 
the  individual. 

Of  the  incisors  shown  in  this  illustration,  only  the  centrals 
are  affected.  The  calcification  of  the  cutting  edges  of  these  is 
occasionally  just  begun  at  birth,  and  if  not  begim  then,  is  usually 
begun  within  one  year.  The  injury,  therefore,  occurs  soon  after 
the  birth  of  the  child  from  some  cause  which  interferes  with 
nutrition.  A  very  curious  fact  in  pathology  is  rendered  promi- 
nent in  this  form  of  atrophy.  It  is  this :  when  the  nutrition  of 
any  single  part  of  the  enamel  organ  is  so  impaired  that  its  func- 
tion is  stopped  or  very  seriously  disturbed,  that  particular  part 
does  not  recover,  and  no  additional  enamel  is  formed  by  that 
part.  This  will  appear  more  prominently  in  the  histological 
specimens.  It  is  for  this  reason  that  these  teeth  have  the  peculiar 
rounded  appearance  of  the  cutting  edge.  The  enamel  organ 
of  that  part  is  arrested  in  its  work  at  the  very  beginning  of  the 
(ialcification.  and  therefore  the  immediate  incisal  edge  fails 
entirely.  The  rest  of  the  organ  goes  on  with  its  work  after  the 
recovery  and  the  tooth  is  drawn  in  over  the  scar.  In  the  incisors 
this  form  of  atrophy  is  apt  to  be  attacked  by  decay  in  this  incisal 
pit  very  soon  after  the  teeth  have  taken  their  places  in  the  arch. 
They  should  be  filled  at  once  if  decay  is  discovered.  This  par- 
ticular form  of  atrophy  is  seen  less  frequently  than  others. 

The  occlusal  surfaces  of  the  first  molars  are  occasionally 
badly  atrophied  when  the  incisors  have  escaped.  Usually  these 
have  just  begun  their  calcification  at  birth,  and  occasionally  the 
calcification  of  the  central  incisors  does  not  begin  for  one  year 
after  birth.  In  such  cases  a  severe  illness  may  injure  the  molars 
and  not  injure  the  incisors. 

Much  the  more  common  forms  are  those  illustrated  in  Fig- 
ures 2  and  3,  the  ilhistrations  showing  rather  bad  cases.  In 
Figure  2  the  deformity  is  confined  to  the  cutting  edges,  appar- 


ATKOPHY    OF    THE    TEETH.  9 

ently,  of  the  central  and  lateral  incisors  above  and  below,  and 
the  four  first  molars.  In  the  case  here  illustrated  the  whole  of  the 
incisal  edge  of  each  of  the  incisors  above  and  below  is  dwarfed 
and  shortened.  This  dwarfed  portion  ends  abruptly  toward  the 
gingival.  This  is  common  in  these  cases.  In  many  there  is  more 
or  less  rounding  down  of  the  well-formed  part  of  the  crown  to 
the  deformed  part,  but  often  it  is  so  abrupt  as  to  form  a  square 
shoulder  along  which  there  is  apt  to  be  a  series  of  sharp,  deep 
pits.  In  the  case  from  which  Figure  2  is  taken  there  are  no  pits 
whatever,  and  the  deformity  consists  purely  in  the  dwarfing  of 
the  incisal  edges.  But  the  entire  occlusal  surfaces  of  the  molars 
were  in  very  bad  condition  because  of  dwarfing  that  presented 
many  abrupt  fissures  in  which  decay  began  almost  inunediately 
after  they  had  come  through  the  gums.  In  such  cases  as  this  the 
appearance  of  the  incisor  teeth  may  be  much  improved  by  grind- 
ing away  the  dwarfed  portion  and  shortening  the  cuspids  a  little 
to  correspond  with  them.  The  teeth  may  appear  a  little  short, 
but  that  is  sometimes  much  less  noticeable  than  the  blemish. 

In  other  cases,  occurring  in  the  same  locality  and  affecting 
the  same  teeth,  there  may  be  but  little  dwarfing  of  the  incisal 
edges  of  the  incisors.  The  effect  may  be  but  a  slight  groove  that 
may  be  smooth  or  more  or  less  pitted,  or  in  cases  of  a  still  milder 
type  the  distinct  groove  may  be  lacking  and  a  row  of  fine  pits  in 
the  enamel  will  be  the  only  deformity.  Generally,  the  effect  is 
more  marked  in  the  occlusal  surfaces  of  the  first  molars  than  in 
the  incisors. 

In  the  case  illustrated  in  Figure  3  the  injury  has  occurred 
later,  when  the  child  was  between  three  and  four  years  old.  The 
incisal  portion  of  the  incisors  had  been  formed,  and,  therefore, 
there  is  no  dwarfing  of  this  portion  of  these  teeth.  But  there  is 
a  very  marked  groove  encircling  the  crowns  of  the  incisors  and 
cuspids,  marked  with  pits,  with  smoothly  rounded  bottoms.  Both 
the  groove  and  the  pits  in  the  groove  are  abrupt  toward  the  gingi- 
val and  thin  away  toward  the  incisal.  This  is  a  constant  charac- 
teristic of  these  deformities,  which  will  be  readily  understood 
by  a  study  of  the  histological  sections  and  the  calcification  lines 
of  Ritzeus.  The  circular  form  of  this  deformity,  as  it  passes 
from  tooth  to  tooth  across  the  front  of  the  mouth,  is  well  marked 
in  Figure  3 ;  indeed,  it  presents  rather  more  of  the  circular  form 
than  usual,  indicating  especially  that  the  cuspids  were  a  little 
later  than  usual  in  their  calcification,  and  for  that  reason  the 
mark  is  nearer  the  incisal  edge  in  proportion  to  the  position  on 
the  incisors  than  it  would  otherwise  have  been. 


10  PATHOLOGY   OP   THE    HARD   TISSUES   OF    THE   TEETH. 

It  is  not  frequent  that  we  see  so  severe  a  mark  as  here  shown 
so  high  upon  the  labial  surfaces  of  the  incisors.  It  seems  to  be 
a  general  rule  that  the  higher  upon  the  teeth  the  less  marked  is 
the  deformity.  Pretty  generally,  in  this  position  on  the  cen- 
trals, the  mark  is  a  shallow  groove,  more  or  less  pitted,  or  a  row 
of  pits  without  a  distinct  groove.  In  all  of  these  cases  the  lower 
teeth  bear  marks  similar  to  those  in  the  upper. 

In  Figure  4  a  case  is  illustrated  that  is  somewhat  out  of  the 
usual  form  in  several  particulars.  When  the  impression  for  the 
cast  from  which  the  illustration  was  made  was  taken,  the  cuspids 
had  not  come  through  the  gums,  but  one  of  the  first  bicuspids  had 
erupted,  and,  to  my  surprise,  showed  a  deep  mark  encircling  the 
point  of  the  buccal  cusp.  Also  the  history  of  the  case  shows  that 
the  lateral  incisors  did  not  erupt  for  two  years  after  the  centrals 
had  taken  their  places.  In  the  centrals  the  incisal  edges  are  fully 
formed,  but  there  is  a  deep  groove  with  rounded  pits  encircling 
the  crowns  at  nearly  mid-length,  while  nearly  the  whole  incisal 
half  of  the  laterals  is  badly  deformed.  This  indicates  that  the 
beginning  of  the  calcification  of  these  teeth  was  late,  as  compared 
with  that  of  the  centrals.  This  particular  form  of  deformity  of 
the  lateral  incisors  is  not  very  frequent,  but  yet  a  considerable 
number  have  been  seen,  quite  enough  to  indicate  a  tendency  to 
this  particular  deformity.  In  the  common  vernacular  this  has 
been  called  the  inverted  finger  nail  deformity.  K  we  imagine  the 
finger  nail  taken  up  and  turned  with  the  convex  side  down  and 
set  back  in  the  end  of  the  finger,  we  would  have  something  very 
lilce  this  deformity.  The  whole  appearance  of  this  case  at  the 
time  of  my  observation  of  it,  indicated  imusual  irregularity  of 
the  time  of  calcification  and  eruption  of  the  different  teeth.  The 
first  molars,  both  above  and  below,  had  already  been  destroyed 
by  decay,  beginning  in  the  deformity  of  the  occlusal  surfaces. 

Figures  5  and  6  show  a  lower  incisor  with  a  double  deform- 
ity. Figure  5  is  a  view  of  the  labial  surface,  and  Figure  6  of  the 
mesial  surface.  The  dotted  lines  show  the  normal  tooth  form. 
The  two,  taken  together,  show  the  extent  of  the  dwarfing  of  the 
crown  of  the  tooth.  In  this  case  the  surface  of  the  enamel  was 
smooth  and  without  pits. 

Figure  7  shows  an  upper  central  very  badly  deformed.  This 
is  also  a  double  deformity  and  was  further  injured  by  decay 
starting  in  pits  in  the  abrupt  portion  of  the  groove  nearest  the 
incisal.  The  sharp,  deep  pits  shown  along  the  line  of  the  second 
groove  have  not  been  caused  by  decay,  but  were  there  when  the 
tooth  came  through  the  gums.    These  teeth  are  from  different 


Fig.    8.      Atrophy   of   incisors  and   cuspids  showing   no    discoloration, 
mouth  cf  gnrl   eighteen  years  of  age. 


Photographed    di  rect    from 


FiQ.  9. 


1            ^ 

l'                         \ 

\ 

.    t 

\\ 

\     '■' 

1' 

Fig.   10. 


Fig.  9.  Outlines  of  the  incisors  and  cuspids  and  of  the  first  molars,  somewliat  enlarged,  over  which 
lines  are  drawn  representing  average  positions  at  which  atropliy  marks  will  occur  at  the  ages  named  in 
years  by  the  numerals  attached.  In  these  0  represents  birth,  1  one  year,  2  two  years  of  age,  etc.  Tlie 
rule  is  that  in  atrophies  occurring  before  the  sixth  year  the  bicuspids  and  second  molars  are  not 
marked. 

Fig.  10.  Diagiammatic  illustration  of  the  lines  of  Retzius,  or  incremental  liues  in  tlie  growth 
of   the   enamel,   showing   their   flirection   in    the   different  portions  of  the   enamel   cap. 


ATBOPHY   OF   THE   TEETH.  11 

persons,  and  in  both  cases  were  extracted  in  order  to  remedy 
the  defect  with  artificial  teeth.  This  seems  to  have  been  done 
under  the  mistaken  notion  that  the  roots  of  the  teeth  would  not 
be  good  for  artificial  crowns.  Extended  observation  shows  that 
the  roots  of  such  teeth  are  as  apt  to  be  well  developed  and  as 
good  for  crowning  as  those  of  any  other  teeth.  When  the  crowns 
are  so  badly  deformed  as  to  render  such  proceedings  necessaiy, 
artificial  crowns  should  be  resorted  to,  rather  than  the  removal 
of  the  teeth.  There  is  a  hope  that  in  the  future  such  teeth  may  be 
restored  to  a  comely  appearance  by  means  of  porcelain.  In  case 
the  crowning  involves  the  removal  of  the  pulp,  this  should  be 
delayed  as  long  as  possible  in  order  that  the  roots  may  be  fully 
formed  and  the  apical  foramen  reduced  to  a  small  size.  One 
should  wait  until  the  patient  is  sixteen  to  eighteen  years  old,  and 
twenty  would  be  still  better.  In  many  cases  of  considerable  actual 
deformity  of  the  teeth  from  atrophy  the  color  remains  very  per- 
fect, and  in  this  case,  if  the  incisal  edges  of  the  incisors  are  fairly 
complete,  the  deformity  is  not  prominently  noticeable,  as  is 
shown  in  Figure  8,  from  a  photograph  taken  directly  from  the 
mouth. 

Etiology. 

Atrophy  of  the  teeth  is  always  caused  by  some  illness  that 
has  interfered  with  nutrition  at  the  time  the  particular  parts  of 
the  teeth  affected  were  in  process  of  calcification.  My  attention 
was  strongly  called  to  this  through  a  controversy  between  Mr. 
Hutchinson  of  London,  and  Dr.  Magitot,  of  Paris,  who  took 
opposite  views  some  thirty  or  forty  years  ago.  From  Mr.  Hutch- 
inson's observations  he  was  led  to  believe  at  first  that  all  of  these 
cases  of  atrophy  were  caused  by  inherited  syphilis,  while  Dr. 
Magitot  had  come  to  the  conclusion  that  they  were  due  to 
eclampsia.  This  controversy  led  to  a  closer  study  of  this  whole 
subject,  and  finally  Mr.  Hutchinson  yielded  the  point  so  far  as 
to  say  that  inherited  syphilis  was  a  frequent  cause,  and  for  many 
years  held  that  the  type  shown  in  Figure  1  was  always  caused 
by  inherited  syi^hilis.  That  form,  therefore,  has  been  called  the 
Hutchinson  tooth.  As  showing  how  errors  are  liable  to  be  per- 
petuated, most  of  the  books  on  general  medicine,  surgery  and 
venereal  diseases,  which  mention  these  deformities  at  all,  ascribe 
them  to  inherited  syphilis,  following  the  first  writings  of  Mr. 
Hutchinson  without  further  investigation.  They  are  continually 
accusing  innocent  persons  of  crime. 

The  author  has  followed  this  subject  pretty  carefully  ever 
since  Mr.  Hutchinson  wrote,  adding  observation  after  observa- 


12  PATHOLOGY    OF    THE    HARD   TISSUES    OF    THE   TEETH. 

tion,  and  has  arrived  at  the  conclusion  that  there  is  no  special 
form  of  disease  that  is  especially  blamable  for  this  affliction,  but 
that  any  form  of  disease  that  seriously  interferes  with  nutrition 
is  liable  to  bring  about  this  result,  i.  e.,  that  it  is  not  the  partic- 
ular form  of  disease,  Imt  that  it  is  the  condition  of  malnutrition 
that  is  the  cause,  no  matter  what  the  disease  which  has  induced 
that  condition.  I  have  seen  eases  of  typical  Hutchinson  teeth 
which  were  certainly  in  no  way  connected  with  a  syphilitic  taint 
of  any  kind. 

Some  of  these  observations  may  be  of  interest.  Mr.  and  Mrs. 
B.,  known  by  the  author  intimately  from  childhood,  had  a  child 
which  seemed  healthy  at  birth,  but  soon  afterward  became  anemic 
and  did  very  badly  for  two  years.  Growth  was  a  failure  during 
that  time,  and  it  was  with  great  difficulty  that  the  child  was  kept 
alive.  In  its  third  year,  however,  the  child  recovered  and  became 
strong  and  healthy  and  developed  well.  When  the  permanent 
teeth  came  through  the  gums,  almost  the  iucisal  third  of  the  cen- 
trals and  laterals  was  badly  dwarfed,  the  points  of  the  cuspids 
had  failed  and  the  occlusal  surfaces  of  all  of  the  first  molars 
were  badly  atrophied. 

In  another  case  a  kinswoman  was  visiting  at  my  house  with 
a  little  girl  two  and  a  half  years  old.  The  child  had  not  been  very 
well  for  some  time,  though  she  showed  no  particular  form  of  ill- 
ness. She  would  play  much  of  the  time,  but  seemed  to  get  very 
tired.  One  day  I  was  suddenly  called  to  her  and  found  her  appar- 
ently dead,  a  condition  that  had  been  preceded  by  a  violent  clonic 
spasm.  I  instituted  artificial  respiration  at  once,  and  after  a  few 
moments  there  was  a  sigh  and  directly  another,  and  within  a  few 
minutes  the  respiration  and  circulation  were  reestablished.  The 
child  dropped  to  sleep  almost  immediately,  while  yet  in  my  arms, 
and  seeing  that  the  breathing  was  sufficiently  full  and  regular, 
I  laid  her  on  a  couch  and  left  her  mother  to  watch  her.  She  slept 
three  hours,  and  when  she  awoke  she  was  ready  to  play  again. 
She  remained  rather  dull  for  a  month,  when  the  condition  seemed 
to  pass  away.  There  was  l)ut  the  one  spasm.  But  when  the  per- 
manent teeth  came  through  they  were  dceph'  marked,  corre- 
sponding with  the  time  of  this  occurrence. 

I  attended  a  eliild  two  and  a  half  years  old  through  a  severe 
case  of  typhoid  fever.  When  the  permanent  teeth  came  through 
they  were  marked  with  a  deep  groove,  irregularly  pitted,  similar 
to  Figure  3,  but  not  so  high  u))  on  the  crowns. 

An  English  woman  broiiglit  lier  child  to  me  on  account  of 
a  very  ugly  marking  of  the  incisors  which  had  just  (-omc  through 


ATBOPHY   OF   THE    TEETH.  13 

the  gums.  In  reply  to  my  inquiries  she  could  not  remember 
that  the  child  had  had  an  illness  of  any  kind.  The  boy  had  always 
been  healthy  and  had  escaped  all  of  the  infantile  diseases.  Being 
convinced  that  something  had  occurred  that  would  have  been 
noted,  I  asked  her  if  the  child  had  had  any  kind  of  an  injury. 
This  quickly  brought  out  the  statement  that  the  child  had  had  a 
severe  burn,  a  scald,  on  the  side  and  back,  that  had  healed  slowly 
after  much  suppuration.  Indeed,  the  child  had  been  very  ill  with 
septicemia  for  a  month  or  six  weeks.  The  time  corresponded 
with  the  marks  upon  the  teeth. 

Cases  like  these,  but  every  one  different  in  detail,  could 
be  multiplied  almost  indefinitely.  Scarlet  fever,  measles  and 
whooping-cough  come  in  for  a  large  share  in  producing  these 
marks.  My  observations  for  some  time  led  me  to  believe  that 
scarlet  fever  and  measles  are  most  often  to  blame  for  the  rows 
of  fine  pits,  but  of  late  I  have  found  so  many  of  these  following 
other  forms  of  disease  that  I  am  led  to  doubt  the  distinguishing 
features  of  these  marks.  Certainly,  hereditary  syphilis  comes 
in  for  its  full  share  of  these  cases. 

On  the  other  hand  we  can  not  say,  at  least  I  can  not,  that 
marked  teeth  will  result  from  this  or  that  illness.  If  the  hair 
falls  out  or  the  finger  nails  show  a  groove  after  an  illness  we  are 
apt  to  find  the  teeth  marked  also.  Very  many  of  the  cases  that 
I  have  noted  and  watched  for  the  coming  of  the  permanent  teeth 
have  presented  teeth  without  a  blemish.  Indeed,  among  all  of 
the  cases  that  I  have  noted  and  watched,  the  marked  teeth  have 
been  the  exception  rather  than  the  rule.  Still,  it  remains  true 
that  when  I  have  been  able  to  obtain  a  satisfactory  history,  the 
marked  teeth  have  coincided  in  time  with  some  form  of  disease 
that  might  well  have  interfered  seriously  with  the  nutritive  proc- 
esses. The  history  is  not  always  easy  to  get,  even  among  intel- 
ligent people.  I  once  remarked  to  a  lady  in  my  chair  that  she 
had  been  very  sick  with  scarlet  fever  when  she  was  about  two 
years  old.  She  was  very  sure  she  had  not,  for  she  had  neV^er  been 
told  of  such  an  occurrence.  AVhen  I  explained  that  accurate 
knowledge  of  the  facts  was  of  considerable  scientific  value  she 
said  she  would  question  her  mother  regarding  it.  The  next  day 
I  received  a  note  saying  her  mother 's  story  agreed  with  my  sup- 
position, both  as  to  the  particular  disease  and  the  date  of  the 
illness.  I  have  seen  many  of  these  cases,  however,  in  which  I 
could  find  no  history  of  the  illness  causing  them. 

As  an  assistance  in  searching  for  the  cause  that  has  led  to 
atrophy  in  cases  coming  before  us.  I  introduce  a  diagrammatic 


14  PATHOLOGY    OF    THE    HAED    TISSUES   OF   THE   TEETH. 

chart,  or  index,  indicating  by  lines  across  the  incisors,  cuspids 
and  first  molars,  the  positions  the  grooves  across  the  teeth 
assume  because  of  disease  occurring  at  different  ages  of  the 
child.  Figure  9.  These  lines  have  been  varied  a  little  from  the 
true  contemporaneous  calcification  lines  to  suit  better  the  appar- 
ent positions  upon  teeth  that  are  shortened  by  severe  atrophy. 
This  chart  will  point  out  the  age  at  which  any  injury  occurred 
as  well,  perhaps,  as  it  can  be  done  in  a  chart  of  this  character, 
which,  of  course,  is  founded  upon  averages.  Pretty  wide  varia- 
tions will  occur  in  the  time  of  the  calcification  of  the  teeth  of 
individuals,  and  also  between  the  several  teeth  of  the  same  indi- 
vidual. There  is  certainly  as  much  variation  as  eighteen  months 
in  the  time  of  the  beginning  of  the  calcification  of  the  central 
incisors,  and  a  greater  range  possibly  with  all  of  the  other  teeth, 
except  the  first  molars.  These  latter  are  perhaps  the  most  con- 
stant. But  these  certainly  vary  from  the  twenty-fifth  week  of 
uterine  life  to  something  near  six  months  after  birth. 

The  chart  is  intended  to  give  only  a  general  average  as  to 
the  time  of  the  illness  that  has  caused  these  injuries. 

HisToiiOGiCAii  Chabactees  in  Atrophy  of  the  Teeth. 

In  presenting  the  histological  characteristics  in  atrophy  of 
the  teeth,  it  may  be  stated  that  all  of  the  cases  thus  far  examined 
by  myself,  no  matter  how  different  their  outward  appearance, 
present  one  plan  of  departure  from  the  normal  arrangement 
of  tissues.  The  differences  are  due  only  to  position,  the  number 
of  zones  of  injury  and  in  the  details  of  severitj^.  This  plan  is 
inseparably  linked  with  the  plan  of  development  of  the  dental 
tissues.  There  are,  however,  other  forms  of  deformity  of  the 
enamel  in  a  degree  simulating  atrophy,  which  are  entirely  dif- 
ferent in  histological  characters.  Some  of  these  will  be  noted 
later. 

Except  in  the  pits  that  often  accompany  it,  the  zones  of 
injury  in  atrophy  rigidly  follow  the  lines  of  Retzius.  In  the  dia- 
gram, FigTire  10,  the  lines  of  Retzius  are  made  especially  prom- 
inent to  recall  distinctly  their  direction  on  different  parts  of  the 
enamel  cap  of  the  crown  of  the  tooth.  In  microscopic  observa- 
tion these  are  usually  clearly  seen  in  some  parts  of  the  enamel 
cap,  particularly  in  central  labio-lingual  sections.  They  vary, 
however,  indefinitely  in  prominence  in  different  sections,  and  in 
different  parts  of  the  same  section.  Generally,  they  do  not  show 
clearly  in  all  parts  of  a  section,  and  those  who  have  not  studied 
them  carefully  should  refresh  their  memory  as  to  the  course  of 


ATROPHY    OF    THE   TEETH.  15 

these  lines  m  different  positions  on  the  crown  of  the  tooth.  These 
lines  are  the  index  to  the  growth  of  the  enamel  cap.  They  are 
the  real  lines  of  accretion  and  show  distinctly  the  order  in  which 
the  enamel  cap  is  built  up,  layer  after  layer,  in  its  growth.  Thi.s 
growth  begins  at  the  dento-enamel  junction,  in  positions  which 
represent  the  cutting  edge  (or  points  of  the  cusps  in  molars  and 
bicuspids)  and  grows  from  within  outward,  while  the  dentin 
begins  its  growth  at  the  same  point  and  progresses  from  without 
inward.  The  growth  of  dentin  is  always  a  little  in  advance  of 
the  enamel  as  it  grows  from  the  incisal  edge  of  the  front  teeth 
(or  the  points  of  the  cusps  of  other  teeth)  toward  the  gingival 
line. 

Atrophy,  in  all  cases,  consists  of  an  arrest,  or  partial  arrest, 
of  growth  of  both  enamel  and  dentin  in  the  particular  zone  or 
part  of  enamel  and  dentin,  being  developed  at  the  particular 
time.  In  the  milder  cases  growth  is  imperfect,  leaving  certain 
definite  markings  outlining  the  particular  parts  of  the  tissue 
then  being  formed.  In  all  the  severe  cases  the  growth  of  both 
enamel  and  dentin  is  arrested.  There  seems  to  be  no  recover}' 
of  the  part  of  the  enamel  organ  that  was  at  the  time  in  active 
function.  No  more  enamel  whatever  is  formed  over  the  area 
affected  after  recovery  from  the  condition  of  malnutrition, 
except  as  the  new  formation  is  telescoped  over  the  area  of  the 
old.  The  dentin  pulp,  however,  rebegins  its  growth  function 
apparently  immediately  the  condition  of  malnutrition  has 
passed.  But  the  parts  of  the  tooth  which  should  have  been 
formed  during  that  period  are  not  formed  at  all.  A  certain  part 
of  the  tissue  which  should  have  constituted  the  perfect  tooth  has 
been  left  out,  and  the  distortion  of  form  which  we  so  often  see 
results  from  patching  the  second  growth  onto  the  first  and  the 
total  failure  of  particular  portions  of  the  enamel.  This  total 
failure  of  the  enamel  is  not  in  the  direction  of  the  thickness,  but 
is  always  on  the  lines  of  Retzius.  Therefore,  as  we  shall  see  later, 
there  is  not  a  failure  of  the  total  thickness  of  the  enamel  at  any 
point,  except  in  a  few  cases  in  which  the  injury  occurs  at  a  time 
when  calcification  was  just  about  to  begin,  as  sometimes  occurs 
in  the  so-called  Hutchinson  tooth,  and  may,  rarely,  occur  in 
others.  For  instance,  in  the  diagram.  Figure  10,  there  are  four 
layers  of  enamel  represented  over  the  incisal  edge.  If  total 
arrest  of  growth  should  occur  at  the  time  the  first  two  layers  are 
completed,  the  third  and  fourth  layers  will  never  be  formed.  The 
enamel  will  remain  over  the  incisal  edge  with  only  these  two 
layers.    Then  perhaps  the  fifth  and  sixth  layers  shown,  more  or 


16  PATHOLOGY    OF    THE    HARD    TISSXTES   OF    THE    TEETH. 

less,  will  also  fail,  and  the  seventh  and  eighth  layers  will  overlap 
the  first  and  second  somewhere  near  half  their  length,  because 
the  formed  part  of  the  incisal  edge  sinks  into  the  dentin  pulp. 
The  dentin  i^ulp  has  also  stopped  its  growth  at  the  same  time 
and  the  part  that  failed  of  growth  is  left  out  of  the  final  tooth 
form.  These  are  the  fundamental  propositions  presented  in  the 
explanation  of  the  histological  groupings  of  tissue  and  the  short- 
ening of  the  tooth  crown  foimd  in  these  cases. 

In  Figures  11  and  13  I  present  photomicrographs*  made  with 
a  very  low  power,  of  labio-lingual  sections  from  two  atrophied 
teeth,  so  that  the  entire  form  of  the  crown  of  each  may  be  seen. 
Figure  12  is  another  photomicrograph  from  the  same  section  from 
which  Figure  11  was  made,  but  with  greater  amplification.  The 
one  presents  two  zones  of  injury,  while  the  other  has  but  one.  In 
each  of  these  the  malnutrition  was  so  severe  as  to  arrest  the 
growth  of  both  enamel  and  dentin.  In  each  an  injury  has 
occurred,  affecting  the  incisal  edge  of  the  tooth.  By  comparing 
these  with  the  diagram  it  is  easily  seen  that  when  a  certain  thick- 
ness of  growth  of  enamel  had  formed  over  this  part,  development 
was  arrested  and  no  more  enamel  was  formed.  In  each  case  the 
enamel  is  thickest  at  the  incisal  edge  and  thins  away  to  the 
groove  which  encircles  the  tooth  crown,  which  is  here  presented 
in  section.  A  band  of  very  dark  growth  is  seen  under  the  new 
after-growth  of  enamel  following  the  lines  of  Eetzius  on  down 
to  the  dento-enamel  junction.  A  comparison  now  with  the  dia- 
gram shows  that  the  growth  has  been  arrested  on  the  lines  of 
accretion  or  lines  of  Retzius,  as  you  may  please  to  call  these 
Imes,  Figure  10,  in  both  cases.  Also,  it  is  seen  that  the  second 
injury  in  Figure  11  is  similar  in  plan  to  the  first,  differing  in 
detail  only  because  of  the  changed  direction  of  the  lines  of  accre- 
tion. In  Figures  11  and  12  the  incisal  edge  is  broken,  as  usually 
occurs  in  these  thin  edges,  but  Figure  13  is  from  a  tooth  extracted 
soon  after  it  came  through  the  gums  and  all  of  the  tissue  formed 
is  present. 

Figure  14  is  an  illustration  with  a  much  higher  power  of  the 
labial  side  of  the  first  zone  of  injury  shown  in  Figures  11  and  12. 
Figure  15  is  from  the  second  zone  of  injury  on  the  labial  side, 
and  Figure  16  is  from  the  second  zone  of  injury  on  the  lingual 
side.    In  these,  the  tissues  and  the  lines  of  Retzius  are  fairly  well 

•  NoTB. —  In  this  work  any  photographic  illustration  made  by  reflected  light  will 
be  called  a  photograph,  even  when  moderately  magnified.  But  when  transmitted 
light  through  a  thin  section  has  been  used,  it  will  be  called  a  photomicrograph.  It 
has  not  boon  thought  necessary  to  mention  these  terms  in  every  instance. 


Fio.  n. 


Fig.  11.     Section  of  an  incisor  showing  two  zones  ot  :itr()i)hv,  or  two  grooves  in  section.     Magni- 
fied eight  diameters. 


Fjo.  12.     Same  as  No.  11,  but  with  greater  aniplification. 
2a 


Fig.  13.  Section  of  a  cuspid  showing  a  single  very  severe  zone  of  atrophy,  or  a  single  groove  in 
section.  Magnified  eight  diameters.  This  case  shows  well  the  sinking  of  the  incisal  edge  into  the  body 
of  the  crown  of  the  tooth. 


Fig.   14. 


:*-->^r 


Incisal  end. 


Fig.  14.  Atrophy.  A  i)liotoniiurof^iiiijli  uf  a  portion  including:  (be  first  zoiic  of  injury  on  the  labial. 
i.  e.,  that  nearest  the  incisal  edge,  from  the  same  section  shown  in  Figures  11,  12,  with  a  higher  mag- 
nification. In  this  tile  lilies  of  liet/.ins  n.ay  be  seen  in  the  enamel,  also  the  dark  lino  ot  junction 
between  the  enamel  of  first  formation  and  enamel  of  second  formation,  reaching  from  the  dento-enanicl 
junction,  with  the  enamel  of  second  formation  overlapping  that  of  the  first.  The  line  of  interglobular 
spaces  in  the  dentin,  iimning  almost  parallel  with  the  line  of  the  dento-enamel  junction,  is  well  shown. 

Fig.  15.  Atrophy.  A  portion  including  the  second  zone  of  injury  seen  in  Figures  11,  12,  with  a 
higher  masinliraliuu.  lu  lliis  position  the  liiii's  of  lielzius  (li\ei-e  more  .sharpie  from  the  direelion  of 
the  line  of  the  dento-enamel  junction,  and  the  overlapping  ot  the  third  growth  of  enamel  onto  the 
second  is  shorter.  The  discoloration  is  greater.  The  line  ot  interglobular  spaces  is  broader,  and  in  this 
position  diverges  more  shaqily  from  the  line  of  the  dento-enamel  junction.  Otherwise  i(  is  similar  in 
plan  with  the  first  zone  of  injury  shown  in  Figure  14 


Fig.   10. 


S'.— 


B. 


Y 


Fio.  IG.  Atrophy.  The  second  zone  of  injury  on  (he  linijual  side  from  tlio  section  shown  in  Fig- 
ure 11.  It  will  be  seen  that  while  differing  slightly  in  detail,  :ill  of  its  parts  are  similar  to  the 
portions  shown  in  Figures  14,  15. 

Fig.    17.     Lengthwise   section    through   portion    of   crown    of   an   atrophied    tooth.  a.    Direction 

toward   the  crown.  u.    Direction   toward   the  root.         z.    DcnliTi.  c.    Interglobular   spaces.  e. 

Enamel.  s.  AVedge-shaped  piece  separated  by  line  of  injury.  x.  Line  of  injury.  si.  Full  thick- 
ness of  enamel.     Zsiginundij. 


Fio.   IS. 


'.■'"7i'  ■  v'-'j'''' 


FiQ.    20. 


Ftg.  18.  Labial  surface  of  a  central  incisor,  pliolograpljcd  io  show  the  appearance  of  the  groove. 
Tlie  dark  color  In  parts  of  the  groove  makes  it  appear  deeper  than  it  really  is.  A  part  of  a  section  cut 
from  this  tooth  is  shown  in  Figure  20. 

Fia.  19.     Photo^aph  of  the  ling-ual  surface  of  the  same  tooth  shown  in  Figure  IS. 

Fig.  20.  A  photomicrograph  of  a  portion  of  a  section  from  labial  portions  of  the  central  incisor. 
Figures  18.  10,  showing  a  milder  sort  of  injury  from  atrophy,  in  which  the  growth  of  the  enamel  was 
interrupted  but  not  permanently  stopped.  The  line  of  interglobular  spaces  literally  divides  the  dentin 
of  first  formation  from  that  of  the  second.  The  section  was  broken  and  the  parts  placed  in  position. 
A  scrap  of  enamel  was  lost  in  preparation,  as  represented  by  the  dotted  line. 


ATROPHY    OF    THE    TEETH.  17 

shown,  and  by  studying  the  photomicrographs  carefully,  the 
relations  of  the  tissues  formed  before  and  after  the  injury  may 
be  made  out.  It  will  be  noted  in  Figure  14  that  the  one  particu- 
larly dark  band,  which  represents  the  surface  of  the  enamel 
formed  over  tlie  incisal  edge,  is  continued  under  the  enamel  of 
second  formation  to  the  dento-enamel  junction.  Beginning  a 
little  farther  from  the  incisal,  a  line  of  interglobular  si)aces 
appears  in  the  dentin,  and  .running  almost  parallel  with  the 
dento-enamel  junction,  continues  on  toward  the  incisal  edge. 
Faint  traces  of  these  appear  even  in  the  small  picture,  Figure  12. 
With  sufficient  amplification,  this  line  of  interglobular  spaces  is 
found  to  continue  to  the  incisal  edge  and  join  with  the  similar 
line  from  the  opposite  or  lingual  side;  that  is,  in  the  whole  tooth 
it  is  a  sheet  or  zone  of  interglobular  spaces  passing  throughout 
the  full  extent  of  the  dentin,  of  which  this  is  a  section.  This  line 
represents  the  injury  in  the  dentin.  It  also  represents  more.  It 
marks  the  boundaries  of  the  old  and  the  new  formation  of  dentin 
and  is  the  line  on  which  these  have  been  patched  together.  On 
the  other  hand,  the  one  dark  line  in  the  enamel  marks  the  line 
on  which  the  new  formation  of  enamel  is  patched  onto  the  old. 
After  a  very  careful  study  of  sections  from  many  of  these  teeth, 
it  becomes  clear  that  the  part  of  the  tooth  which  should  have 
formed  during  the  stoppage  of  growth  was  not  formed  at  all. 
The  enamel  organ  was  destroyed  through  its  whole  thickness  to 
the  point  where  the  dark  line  limiting  the  first  enamel  forma- 
tion reaches  the  dento-enamel  junction,  and  when  the  second 
formation  Itegan  it  was  telescoped  over  the  old  and  laid  down 
upon  it,  as  shown  in  the  illustration.  The  crown  of  the  tooth  was 
shortened  that  much,  certainly,  and  may  have  been  shortened 
very  much  more.  When  we  study  carefully  Figure  13,  with  its 
single  line  of  injury,  and  note  how  the  little  part  of  the  incisal 
edge  formed  before  the  injury  is  literally  simken  into  that  por- 
tion formed  later,  we  must  conclude  that  the  shortening  is  much 
greater  than  that  shown  by  the  apparent  telescoping  of  the  parts. 
In  the  dentin  the  same  thing  occurs,  only  that  it  is  expressed  dif- 
ferently because  of  the  different  character  of  the  tissue.  The 
line  of  interglobular  spaces  shows  where  the  second  growth  was 
telescoped  into  the  first. 

A  study  of  Figures  15  and  16  shows  the  same  plan  in  the 
arrangement  of  the  tissue  in  the  second  zone  of  injury,  including 
the  overlapping  of  the  new  enamel  onto  the  old  and  the  accom- 
panying line  of  interglobular  spaces  in  the  dentin.  The  shorter 
overlapping  of  the  enamel  at  the  point  of  injury  is  due  to  the 


18  PATHOLOGY    OF    THE    HARD   TISSUES   OF    THE    TEETH. 

changed  direction  of  the  lines  of  growth.  The  actual  shortening 
of  the  tooth  may  have  been  much  greater.  When  we  study  the 
short  and  stumpy  forms  of  many  of  the  crowns  of  these  atro- 
phied teeth,  we  must  conclude  that  the  shortening  is  often  very 
much  greater  than  this  overlapping.  It  is  this  shortening  and 
telescoping  together  of  the  different  parts  that  is  responsible 
for  the  greater  part  of  the  distortion  of  form  so  often  observed 
in  these  teeth.  It  appears  certain  that  the  tendency  is  to  form 
each  of  the  parts  on  the  lines  that  each  would  have  had  at  the 
specified  time  of  growth  if  thei-e  had  been  no  interruption  of  the 
growth. 

We  may  gain  another  view  of  this  by  studying  the  lines  of 
the  labial  dento-enamel  junction.  In  the  study  of  sections  of 
many  human  incisor  and  cuspid  teeth,  this  line  is  found  to  form 
a  continuous  curve  from  the  incisal  edge  to  the  gingival  line,  as 
seen  in  the  diagram,  Figure  10.  The  amount  of  cui-ve  may  vary 
indefinitely,  but  it  is  always  a  continuous  curve  in  every  normal 
tooth.  In  studying  sections  of  atrophied  teeth,  this  cui-ve  is 
found  broken  by  a  recurve  at  the  zone  of  injury  in  every  case, 
even  in  the  lighter  forms  in  which  growth  seems  not  to  have 
been  completely  arrested.  This  disturbance  of  the  direction  of 
this  line  seems  to  be  due  to  the  effort  to  form  the  second  part 
on  the  lines  that  would  have  been  laid  down  at  that  time  if  the 
growth  had  been  going  on  regularly,  and  the  larger  and  smaller 
are  patched  together.  In  the  dentin  the  growth  has  been  in  abey- 
ance and  the  growth  begins  on  the  lines  on  which  it  was  left  off. 
But  immediately  the  tendency  is  to  enlarge  to  the  greater  out- 
line of  the  tooth  as  it  would  have  been  at  the  time  had  the  growth 
not  been  interrupted.  This  causes  a  recurve  in  the  line  of  the 
dento-enamel  junction.  In  the  enamel,  the  telescoping  seems  to 
be  actual.  That  part  of  the  enamel  organ  that  had  not  arrived 
at  the  period  of  enamel  building  is  uninjured  and  is  pushed  for- 
ward over  the  previously  formed  enamel  and  lays  down  its  layers 
of  the  second  growth  of  enamel  thus  far  over  the  old.  No  other 
explanation  of  the  phenomena  is  presented  after  the  study  of 
numerous  cases. 

The  discoloration  that  occurs  in  these  teeth  would  seem  to 
be  an  essential  characteristic,  if  it  were  judged  entirely  by  the 
teeth  obtained  for  making  sections.  This  material  is  very  diffi- 
cult to  find.  Only  extracted  teeth  can  be  used,  of  course,  and  few 
of  them  are  extracted  until  so  badly  decayed  that  they  are  use- 
less, except  those  that  are  so  badly  discolored  that  patients  and 
their  friends  urge  their  removal  on  that  account.    Examinations 


KiO.    22. 


Figs.  21.  22.  Root  of  tuolh  parted  on  lines  of  ffrowtli.  I'liotographed  from  the  specimen  extractod 
by  the  author.  Photographs  of  a  bicuspid  tooth  which  had  a  zone  of  injury  from  atrophy  mid-length 
of  the  root,  and  which  was  pulled  apart  in  telescope  form  alone:  the  line  of  injury,  i.  o.,  the  line  of 
interglobular  spaces.  In  Figure  21  the  parts  are  photographed  in  normal  position.  In  Figure  22  the 
two  parts  are  separated,  showing  how  they  are  telescoped  together. 


ATROPHY   OF   THE   TEETH.  19 

in  the  mouth  reveal  many  cases  of  very  considerable  deformity 
without  notable  discoloration,  as  the  photograph,  Figure  8,  taken 
from  the  mouth,  attests.  Many  of  the  zones  of  injury  show  no 
discoloration. 

Many  writers  have  given  short  descriptions  of  atrophied 
teeth,  scattering  back  for  a  hundred  years.  Most  of  these  have 
dealt  with  the  outward  appearance  only.  Very  few  have  pub- 
lished any  studies  of  the  histological  characters,  and  most  of 
these  have  been  very  brief  and  imperfect.  Among  the  better 
should  be  mentioned  Wedl,  1870;  Baume,  1882;  Walkoff,  1885. 
But  by  far  the  most  important  of  the  studies  that  have  appeared 
is  that  by  Dr.  Otto  Zsigmondy,  of  Vienna,  Austria,  in  a  paper  pre- 
sented at  the  World's  Columbian  Dental  Congress  in  Chicago  in 
1893.  Unfortunately  for  Americans,  no  translation  into  English 
has  been  published.  I  personally  examined  many  of  Dr.  Zsig- 
mondy's  sections  and  learned  further  of  his  conclusions  in  con- 
versation. The  one  thing  that  impressed  me  then,  and  impresses 
me  now,  as  I  reread  his  paper,  is  his  conviction  that  the  tissue 
distortion  has  been  produced  by  a  condition  that  has  been  of  very 
short  duration,  because  the  apparent  zones  of  injury  in  the  dentin 
were  often  —  nearly  always,  indeed  —  so  very  narrow  when  con- 
sidered in  their  relation  to  the  developmental  lines.  He  could 
not,  therefore,  account  for  the  marked  deformity  of  these  teeth. 
At  the  time  he  wrote  he  did  not  have  the  advantage  of  photo- 
micrographic  reproductions,  and  his  illustrations  were  very 
meager  and  insufficient.  One  of  the  best  of  them  is  reproduced 
in  Figure  17. 

Figure  20  is  a  photomicrograph  of  a  section  of  the  labial 
portion  of  a  zone  of  injury  of  the  milder  sort  apparently,  occur- 
ring in  a  central  incisor.  In  this  there  was  considerable  discolor- 
ation of  the  enamel  occurring  irregularly  along  the  line  of  injury 
in  the  labial  surface,  as  shown  in  the  photograph  of  the  tooth. 
Figures  18  and  19.  The  discoloration  in  the  line  of  the  groove 
has  the  effect  of  a  shadow  in  the  photograph  and  makes  the 
groove  appear  deeper  in  the  discolored  portions,  which  is  not 
the  fact.  The  particular  section  from  which  Figure  20  was  made 
was  chosen  from  a  part  showing  the  least  discoloration.  In  this 
case  the  only  distortion  of  the  crown  apparent  in  a  superficial 
view  of  the  tooth  is  the  groove  encircling  the  tooth  and  the  dis- 
coloration. Also,  the  section  shows  that  there  was  not  a  com- 
plete arrest  of  growth  of  the  enamel.  With  a  good  light  the 
enamel  rods  may  be  traced  with  the  microscope  through  the 
darkest  lines  of  the  section,  and  they  are  seen  to  be  well  formed. 


20  PATHOLOGY   OF    THE    HARD    TISSUES   OF    THE   TEETH. 

There  is  no  appearance  of  the  telescoping  process.  The  groove 
in  the  enamel  appears  much  less  pronounced  in  the  section  when 
highly  magnified  as  shown,  than  it  does  in  the  photographs  of 
the  tooth.  In  the  dentin,  however,  the  injury  is  very  severe,  as 
shown  by  the  clean-cut  continuous  line  of  interglobular  spaces, 
which  literally  cut  the  dentin  first  formed  from  that  formed  later, 
and  in  the  examination  of  the  labial  line  of  the  dento-enamel 
junction  in  the  full  section,  it  is  found  to  be  distorted  by  a 
recurve,  showing  the  interference  with  growth  to  have  been  pro- 
found and  that  some  real  shortening  of  the  tooth  must  have 
occurred. 

As  a  further  illustration  of  the  possibilities  in  this  class  of 
injuries,  I  present  two  photographs,  Figures  21  and  22,  of  a 
bicuspid  tooth  showing  the  separation  of  the  telescoped  parts  in 
an  injury  of  this  kind  occurring  mid-length  of  the  root.  I 
extracted  this  tooth  myself.  The  patient,  a  stranger,  applied 
for  relief  from  caries  of  bone  of  the  upper  jaw,  and  this  tooth 
was  situated  on  the  border  of  the  carious  area  in  such  position 
that  it  seemed  to  be  best  to  remove  it,  though  the  tooth  and  its 
individual  alveolar  process  were  otherwise  in  good  condition. 
At  the  moment  of  removing  the  tooth,  it  was  noticed  that  the 
apical  portion  of  the  root  did  not  come  away,  but  was  pulled 
from  its  place  and  remained  loose  in  the  alveolus.  Laying  the 
tooth  on  the  bracket  with  the  forceps,  this  apical  portion  was 
picked  out  with  the  foil  pliers  and  laid  with  the  tooth  for  after 
examination,  because  it  seemed  to  be  a  very  curious  break.  The 
operation  was  completed  and  the  patient  dismissed  with  an 
appointment  to  return  later  for  further  treatment.  On  exam- 
ination, this  tooth  and  root  were  found  to  have  pulled  apart 
like  a  telescope  tube,  and  the  telescoping  was  on  the  lines  of 
growth  of  the  dentin.  Figure  21  shows  the  tooth  and  root  placed 
together  in  the  normal  form,  in  which  a  marks  the  line  of  break. 
In  Figure  22  the  two  parts  are  separated,  showing  how  the  apical 
portion  telescopes  into  the  bodj^  of  the  root.  I  suppose  there 
was  some  severe  illness  of  short  duration  at  the  time  this  part 
of  the  root  was  developing,  which  prevented  the  deposit  of  cal- 
cium salts,  and  a  sharp,  distinct  and  continuous  line  of  inter- 
globular spaces  occurred.  At  the  time,  the  root  was  developed 
only  as  far  as  shown  in  the  lower  section  of  Figure  22,  and  had 
the  broad  conical  opening  shown  at  li.  The  internal  diameter 
at  the  point  to  which  the  end  of  the  apical  portion  reaches  was  of 
the  size  shown  by  the  end  of  that  piece.  The  result  was  that  the 
solid  dentin  formed  at  that  time  represented  only  the  lower 


M 


Fig.   23. 


Fig.  23.  A  portion  of  a  section  throiigli  a  central  incisor,  showing  atrophy  of  the  severer  sort. 
The  plan  of  the  injury,  and  the  telescoping  together  of  the  parts,  is  seen  to  be  the  same  as  in  Figures  14, 
15,  b\it  the  discoloration  is  much  less.  The  thin  incisal  edge  had  been  gro\md  away  before  extraction 
in  an  effort  to  improve  the  appearance. 

3b 


Fig.  24.     Portion  of  a  section  from  an  incisor  sliowing  a  zone  of  atrophy  and  the  plan  upon  which 
the  parts  are  telescoped  together.     Tlie  thin  incisal  edge  had  lieen  ground  away  before  extraction. 

3c 


ncisal  end. 


Fig.  2.5.  A  photoiiiicrograpti  from  labial  portion  of  a  section  fiuin  an  incisor  tooth  which  showed 
but  faint  traces  of  an  atrophy  mark  on  the  surface  of  the  enamel.  The  markings  in  both  the  enamel 
and  dentin  arc  such  as  are  found  in  the  milder  forms  of  atrophy. 


Fig.  26.  Photograph  of  a  bicuspid,  showing  imperfectly  a  slight  groove  from  atrophy  near  the 
junction  of  the  middle  and  gingival  thirds  of  the  crown.     See  Tigiu'es  27,  28. 

Fig.  27.  The  bicuspid  shown  in  Figure  26  split  mesio-distally  and  the  cut  surface  photographed  as 
an  opaque  object.  Note  a  broad  zone  of  shadow  in  the  dentin,  extending  in  a  semi-circular  form  from 
the  groove  on  the  mesial  to  the  groove  on  the  distal  side.     See  also  Figure  29. 


i 


Fig.   28. 


Fig.  28.  A  photomicrograph  from  a  portion  of  a  section  of  the  bicuspid  shown  in  Figures  26,  27, 
showing  zone  of  shadow  in  the  dentin  as  a  result  of  interference  with  nutrition.  Markings  of  this  char- 
acter are  found  in  the  mildest  forms  of  interference  with  nutrition  that  show  atrophy  marks. 


Fig.   29. 


Fig.  20.  A  photomicrograph  from  section  of  atrophied  tooth  cut  diagonally  to  the  zone  of  injury 
and  ser\ing  to  exaggerate  the  width  of  the  zone  of  interglobular  spaces  in  the  dentin.  This  gives  a 
stronger  representation  of  the  real  injury  to  the  dentin. 


ATROPHY   OF    THE    TEETH.  21 

square  end  of  the  upper  piece.  This  was  broken  in  the  effort 
to  extract  and  the  root  pulled  apart  on  the  line  of  the  area  of 
interglobular  spaces,  the  line  representing  the  lines  of  the  pi-oc- 
ess  of  growth. 

The  patient  failed  to  keep  his  appointment  for  further  treat- 
ment and  was  not  seen  again.  The  opportimity  to  inquire  into 
the  nature  of  the  nutritional  disturbance  that  had  caused  this 
rare  form  of  injury  was  lost.  The  specimen,  however,  tells  its 
own  story  clearly.  This  case  shows  that  the  root  of  a  tooth  may 
also  be  injured  by  atrophy,  though  such  an  extreme  occurrence 
as  this  must  be  rare. 

I  have  noted  a  considerable  number  of  cases  in  which  a  zone 
of  injury  occurred  in  the  dentin  beginning  below  the  gingival 
line,  as  in  the  case  shown  in  Figures  21,  22,  though  they  are  far 
more  rare  than  those  occurring  in  the  crown  of  the  tooth.  In 
Figure  11  there  is  such  a  zone  of  injury  which  may  be  seen  even 
in  that  slight  amplification,  in  the  disturbance  of  the  outlines  of 
the  enamel  and  some  faint  shadows  representing  the  lines  of 
interglobular  spaces.  With  medium  powers  of  the  microscope, 
these  latter  are  prominent  objects. 

Figure  23  represents  another  case  of  atrophy  of  the  graver 
sort,  occurring  in  a  central  incisor,  in  which  but  little  discolor- 
ation is  apparent.  The  wide  overlapping  of  the  new  onto  the 
older  enamel,  the  complete  breakage  of  the  enamel  rods  along  the 
line  of  junction  of  the  two,  the  change  in  the  course  of  the  enamel 
rods  in  the  two  formations  of  enamel  and  the  profound  disturb- 
ance of  and  recurving  of  the  labial  dento-enamel  junction,  all 
point  to  a  long  suspension  of  nutrition  and  account  for  the  grave 
distortion  of  the  form  of  the  tooth.  This  is  much  like  that  shown 
in  Figure  13.  The  line  of  interglobular  spaces  is  sharp  and 
severe,  but  very  narrow,  and  the  dentin  is  normal  immediately 
on  either  side.  The  incisal  edge  had  been  ground  away  in  the 
endeavor  to  improve  the  appearance  before  the  tooth,  with  the 
other  incisors,  was  extracted.  About  one-third  of  the  normal 
length  of  the  crown  had  been  missing. 

Figure  24  represents  another  similar  case,  but  with  rather 
more  discoloration.  The  incisal  edge  of  this  had  also  been 
groimd  away  in  the  effort  to  improve  the  appearance  before 
resorting  to  extraction.  In  this  the  main  features  are  again 
repeated;  it  shows  the  same  line  of  demarkation  between  the 
old  and  new  enamel,  the  same  distortion  by  recurve  of  the 
labial  dento-enamel  junction  and  the  same  sharp  line  of  inter- 
globular spaces.     In  this  particular  case  the  character  of  the 


22  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE    TEETH. 

line  of  interglobular  spaces  is  almost  obscured  by  being  tilled 
with  balsam  in  mounting  the  section. 

Figure  25  represents  a  case  that  was  apparently  of  the 
mildest  description.  The  only  outward  appearance  was  a  band 
of  slightly  dark  color  across  the  labial  surface  of  the  tooth.  One 
not  searching  for  cases  of  this  character  might  have  passed  the 
tooth  as  normal.  The  tissue  reveals  a  pronounced  disturbance 
in  the  same  particulars  as  in  the  more  severe  cases,  only  not  so 
grave.  The  enamel  rods  pass  through  all  of  the  darkened  lines 
without  a  break,  and  there  are  almost  no  interglobular  spaces  in 
the  dentin.  A  sharp  curve  and  recurve  in  the  dentinal  tubules 
give  the  appearance  of  a  very  distinct  line  of  injury,  however. 
The  line  of  the  labial  dento-enamel  junction  is  also  considerably 
disturbed. 

The  next  case  is  very  curious  in  several  respects.  It  is  a 
bicuspid  tooth  that  showed  a  very  slight  groove  in  the  enamel 
not  far  from  the  gingival  line.  It  was  covered  by  the  overlap- 
ping gum  margin,  except  on  the  buccal  surface.  The  whole  tooth 
was,  perhaps,  as  white  as  any  normal  tooth  and  was  without  any 
discoloration  along  the  line  of  the  groove,  except  that  caused 
by  a  deposit  of  dark,  closely  adherent  serumal  calculus  at  several 
points.  A  photograph  of  this  groove  was  but  a  partial  success, 
as  is  shown  in  Figure  26.  The  tooth  was  then  divided  mesio- 
distally,  preparatory  to  grinding  sections.  In  examining  the 
halves  with  a  pocket  lens,  a  curious  zone  of  injury  in  the  dentin 
was  discovered,  which  was  photographed  at  once  as  an  opaque 
object,  which  is  represented  in  Figure  27.  Two  sections,  two 
thousandths  of  an  inch  thick,  were  prepared  and  mounted  with- 
out removing  them  from  the  cover  glass  on  which  they  were 
ground.  The  sections  were  beautiful.  No  one  would  suspect 
that  there  was  any  zone  of  injury  in  either  dentin  or  enamel. 
The  disturbance  of  the  line  of  the  dento-enamel  junction  and  in 
the  one  section  a  clinging  bit  of  serumal  calculus  were  the  only 
abnormalities  discoverable  by  microscopic  examination.  The 
only  way  I  could  explain  this  was  that  the  something  that  had 
been  seen  and  photographed  had  become  obscured  by  the  balsam. 
The  balsam  was  dissolved  out  and  the  section  dried.  A  zone  of 
fine  interglobular  spaces  was  then  found  with  another  singular 
appearance  in  the  form  of  a  broad  line  of  demarkation,  that  could 
not  be  explained.  The  section  was  remounted  in  a  very  stiff 
balsam  without  using  anything  to  clear  the  dentin,  with  the 
expectation  of  making  a  photomicrograph  the  same  evening. 
Something  prevented,  and  by  the  next  evening,  the  day  having 


ATROPHY    OF    THE    TEETH.  23 

been  unusually  warm,  the  interglobular  spaces  were  again  filled 
with  balsam.  The  shadow,  however,  remained,  and  is  presented 
in  Figure  28.  It  has  since  been  found  that  the  condition  pre- 
sented is  common  to  a  considerable  number  of  the  slighter 
atrophic  injuries. 

Figure  29  is  a  photomicrograph  of  a  labio-lingual  section  cut 
from  near  the  mesial  side  of  an  atrophied  tooth  so  that  the  line 
of  interglobular  spaces  is  cut  through  diagonally.  This  gives 
an  exaggerated  view  of  the  zone  of  injury  to  the  dentin,  but  will 
serve  to  impress  the  fact  that  these  injuries  are  very  severe. 

This  presents  this  subject  from  its  gravest  to  its  slightest 
degree,  in  sufficient  variety  of  cases  to  render  the  conditions 
intelligible. 

Atrophy  of  the  FmsT  Permanent  Molars. 

Atrophy  of  the  first  permanent  molars  should  receive  some 
special  consideration  because  of  its  greater  frequence  and 
because  it  so  generally  leads  to  early  and  rapid  caries  beginning 
in  the  atrophied  portion.  The  plan  of  injury  does  not  differ 
from  that  in  atrophy  of  the  anterior  teeth,  but  the  details  of  the 
injury  are  different  because  of  the  wide  difference  in  the  form 
of  the  tooth.  The  greater  frequence  of  the  occurrence  of  atrophy 
of  these  teeth  is  due  to  the  earlier  beginning  of  calcification.  In 
dissections  of  the  jaws  of  the  fetus  at  term,  I  have  usually  found 
the  calcification  of  this  tooth  just  begun  on  the  points  of  the 
cusps.  Sometimes  there  are  only  small  spiculae,  in  other  cases 
a  more  considerable  part  of  the  cusps  is  calcified,  but  I  have 
never  seen  the  calcification  so  advanced  at  birth  that  the  cusps 
were  united  by  calcified  tissue,  and  evidently  they  are  not  so 
united  rmtil  much  later.  On  the  other  hand,  it  was  only  occa- 
sionally that  the  least  bit  of  calcification  had  occurred  on  the 
central  incisors.  More  often  calcification  does  not  begin  on  these 
until  about  the  end  of  the  first  year.  Therefore,  an  illness  that 
brings  about  serious  malnutrition  during  the  first  year  of  the 
child's  life  is  liable  to  wreck  the  occlusal  surfaces  of  the  first 
molars,  while  all  of  the  other  teeth  escape  injury. 

Atrophy  of  these  teeth  occurring  so  early  is  very  charac- 
teristic if  seen  soon  after  the  eruption  of  the  teeth  and  before 
further  injury  has  occurred  by  breaking  away  the  sharp  spiculae 
representing  the  malformed  cusps  or  by  caries.  But  it  is  exceed- 
ingly difficult  to  obtain  specimens  from  which  to  make  illustra- 
tions. If  the  atrophy  has  occurred  very  early,  or  before  the 
enamel  plates  forming  the  lobes  of  the  teeth  have  joined  together, 


24  PATHOLOGY   OF    THE    HARD    TISSUES    OF    THE    TEETH. 

the  spiculsE  of  cusps  will  stand  much  closer  together  than  the 
cusps  of  the  normal  tooth.  The  whole  of  the  occlusal  surface 
of  the  tooth  is  dwarfed,  often  discolored  and  sunken  into  the 
tooth  crown.  The  pulp  chamber  will  be  nearer  to  the  occlusal 
surface  than  in  the  normally  developed  tooth  in  proportion  to 
the  sinking  of  this  part  into  the  body  of  the  crown.  Figure  30. 
All  around  this  the  enamel  of  second  formation  wells  out  in  the 
form  of  a  broad  collar  to  the  normal  size  of  the  tooth  crown  at 
or  about  the  base  of  what  would  have  been  the  normally  devel- 
oped cusps.  The  whole  of  the  injured  area  is  apt  to  be  rough 
and  pitted,  and  the  pits  and  grooves  are  very  apt  to  be  wide  open. 
This  condition  gives  unusual  opportunity  for  the  beginning  of 
caries  and  the  early  exposure  of  the  pulp.  It  is  for  this  reason 
particularly  that  they  are  so  often  destroyed  very  early.  In 
cases  occurring  a  little  later,  but  before  the  completion  of  the 
occlusal  surface,  the  conditions  inviting  the  beginning  of  caries 
are  equally  bad.  The  cusps  will  stand  further  apart,  are 
stronger,  but  the  central  part  of  the  occlusal  surface  and  the 
outer  slopes  of  the  cusps  are  in  very  bad  shape.  At  a  still  later 
date,  after  the  completion  of  the  occlusal  surface,  the  injury 
appears  as  a  groove  around  the  crown  of  the  tooth  and  is  gen- 
erally of  less  consequence. 

In  all  of  these  cases  the  zone  of  injury  in  the  dentin  is  one 
of  the  very  grave  features,  for  the  reason  that  caries  reaching 
this  zone  of  interglobular  spaces  spreads  through  it  quickly.  It 
has  been  exceedingly  difficult  to  get  material  for  the  illustration 
of  this  for  the  reason  that  very  generallj'  the  occlusal  surfaces 
of  these  teeth  are  destroyed  by  caries  before  their  removal, 
rendering  them  useless  for  this  purpose.  Figures  31,  32  and  33, 
with  their  descriptions,  serve,  however,  to  illustrate  the  condi- 
tion of  the  tissue  injuries  fairly  well,  though  neither  of  them  are 
of  the  severer  forms  of  atrophy.  Figure  31  particularly  shows 
the  line  of  interglobular  spaces  in  the  dentin  extending  across 
the  occlusal  surface  and  dipping  down  gingivally  along  the  axial 
portions  of  the  dento-enamel  junction.  This  figure  also  shows 
well  the  shortening  of  the  crown  between  the  pulp  of  the  tooth 
and  the  occlusal  surface.  From  the  position  of  the  injuries  in 
atrophy,  it  will  be  realized,  from  a  careful  study  of  the  lines  of 
the  injury  to  the  dentin,  that  the  total  shortening  of  the  crown 
of  the  tooth  is  betAveen  the  pulp  and  the  occlusal  surface  in  the 
molars.  It  is  also  between  the  pulp  and  the  incisal  edge,  where 
it  occurs  in  the  incisors  and  cuspids.  This  is  the  reason  that 
pulps  are  so  frequently  exposed  in  the  preparation  of  cavities 


Fig.   30. 


FiQ.  30.  Photograph  of  cast  showing  atrophy  of  a  first  molar.  Note  that  the  occlusal  portion  of 
the  tooth  is  much  reduced  in  size.  This  is  best  appreciated  by  comparison  with  the  second  molar. 
Normally  the  occlusal  surface  of  the  first  molar  is  the  larger  of  the  two. 


'Is, 

)  — ,0 


S*P  o 


3.  n  ""-lS-p 

EJ.  »   r*  *   "^   W 
§ttE§OOM 


-■5o  S-s-j 


r-g-"°3 


P   »  w  ■=  C  ^. - 


en       i-aZr- 
*•      o  3  o  ^ 


"VS 


3 

-. 

U 

g 

0 

3 

^ 

0 

00 

0 

li. 

c 

3 

3 

P 

? 

3 
3 

5' 

I^ 

p 

0 

jq 

5' 

IT 

3- 

ro 

0 

3 

— 

m 

P 

3" 

Cl 

1 

■n 

S- 

■a 

33 

c* 

3- 

■" 

0 

ft- 

2, 

0* 

3'P 

3 

0 

0 

1 

5' 

p' 

3 

a. 

n 

3" 

5 

3 

-1 

era 

0 

0 

(n_wa 

-1 

c 

p 

0" 

p- 

"^  0 

Q,0 

1 

=& 

0 

3 

c 

p* 

a< 

5 

3 

0 

IPJ 

r5 

3 

M 

TT 

P 
0 

3 

0 

0 

0 

S- 

0 
c 

2 

3 

■^ 

p* 

3 

S 

m 

(R 

a. 

S 

3 

s- 

0 

=■ 

ffi- 

0 
0 

0 

3 

5 

3" 

P 

p3 

3 

0 

m 

X 

13 

M 

P 

^ 

F 

" 

P 

p" 

"1 

3- 

d 

P 

c 

-T 

3 

1 

3 

3" 

2' 

0 

n 

a. 

"< 

3 

< 

0 

fU 

•0 

i" 

0 

o" 

CT 

3 

0 

P 

^ 

•< 

^ 

C 

a> 

3 

0 

0 

yi 

» 

2 
0 

iq 

-1 

0 

s 

? 

J- 

c 

;5  3 
3*.. 

CT 

p 

3 

p 

0 

re 

P 

< 

T 

3 

cr 

< 

p 

Q 

c 

w 

1 

•3 

S-H 

3- 

^ill^l 


Q. 
.  3   3-r 


o-^  p  ; 

»   '^   S   5^3 

3  -»   .   rt)  fD  » 


Fia.  32. 


Fig.  32.  A  photomicrograph  with  a  much  higher  power  from  another  tooth  with  a  similar  atrophy 
to  that  shown  in  Figure  31,  in  which  the  section  was  cut  horizontally  or  crosswise.  The  section  through 
the  interglobular  spaces  is,  therefore,  through  that  portion  of  the  line  showing  in  Figure  31,  which 
dips  toward  the  gingival  at  the  buccal  and  lingual  portions  of  the  section.         e.  Enamel.  d.   Dentin. 

8.  s.    Line  of   interglobular  spaces  appearing  as   irregular   dark    blotches   connecting   the   one   with   the 
titbiM"  in  every  direction. 


,^^^?:!^^,t>-'.,:^^^^^_ 


>' 

r 


'S*^ 


Fio.  33.  A  photomicrograph  from  a  portion  of  a  mesio- distal  section  of  a  first  molar  showing  in 
the  section  two  zones  of  interglobular  spaces.  It  shows  only  a  part  of  the  mesial  half  of  tuc  section. 
Note  that  the  line  of  interglobular  spaces  nearest  the  enamel,  the  first  line,  follows  closely  the  dento- 
enamel  junction.  This  follows  the  prominence  of  the  mesial  marginal  ridge  of  dentin  (on  the  left  in 
the  picture)  and  then  dips  down  to  the  gingival.  The  line  of  injury  to  the  enamel  also  rounds  over 
this  prominence  and  again  touches  the  dentin  just  above  the  point  of  ending  of  the  injury  to  the 
dentin.  The  second,  and  more  marked  zone  of  injury  to  the  dentin,  swings  out  quickly  from  the  dento- 
enamel  junction,  on  the  left  in  the  picture,  and  runs  across  much  deeper  in  the  tooth,  showing  the 
amount  of  dentin  formed  before  this  occurred. 


ATROPHY    OF    THE    TEETH.  25 

in  atrophied  teeth.  Dentists  generally  have  not  realized  that 
the  pulps  were  so  close  to  the  surface.  When  it  is  realized  that 
these  sheets  of  interglobular  spaces,  of  which  the  line  of  atrophy 
in  the  dentin  showing  in  Figure  31  and  in  Figure  33  is  a  section, 
spread  through  the  entire  area  of  the  crown  of  the  tooth,  form- 
ing openings  through  which  microorganisms  may  readily  grow, 
it  will  be  understood  why  it  is  so  difficult  to  prevent  the  destruc- 
tion of  these  teeth  by  caries.  It  will  also  be  understood  how 
decay  may  quickly  undermine  the  entire  enamel  cap,  allowing 
it  to  fall  away,  exposing  a  blackened  stump  of  dentin  in  all  of 
the  central  portion  with  jagged  enamel  upon  its  margins,  with 
decay  persisting  around  the  circumference  where  the  line,  or 
sheet,  of  interglobular  spaces  dips  to  the  gingival  near  the  dento- 
enamel  junction.  In  the  child,  one  is  prohibited  from  forming 
a  cavity  of  such  depth  as  required  to  hold  such  a  broad  filling 
because  of  the  nearness  of  the  pulp  of  the  tooth. 

The  grave  significance  of  this  lies  in  the  fact  that  caries 
beginning  in  the  imperfections  of  the  occlusal  surface  quickly 
reaches  this  zone  of  interglobular  spaces  and  spreads  rapidly 
through  it,  undermining  and  destroying  the  whole  occlusal  por- 
tion of  the  tooth.  It  often  happens  that  the  whole  of  this  has 
been  swept  away  so  quickly  that  the  area  is  uncovered  before 
decay  has  proceeded  further  toward  the  pulp.  The  decaying 
area  is  then  fully  exposed  to  the  fluids  of  the  mouth,  and  the 
progress  of  the  caries  is  arrested.  In  this  case,  the  tooth  remains 
as  a  blackened  stump  that  soon  rises  in  its  alveolus  and  occludes 
with  its  fellow,  which  is  generally  in  a  similar  condition,  and 
both  do  good  service.  More  often,  however,  decay  continues 
in  that  portion  of  the  zone  of  injury  referred  to,  that  dips  under 
the  strong  enamel  around  the  margins  of  the  crown.  Being  thus 
protected,  it  continues  to  burrow,  finally  reaching  the  pulp  and 
completing  the  destruction.  This  is  the  general  fate  of  atrophied 
first  permanent  molars.  Case  after  case  comes  before  me  in  the 
great  clinic  of  Northwestern  University  Dental  School,  showing 
atrophy  of  the  anterior  teeth  in  young  people.  The  rule  is  that 
the  first  molars  have  already  been  lost.  Children  from  eight  to 
twelve  years  old  are  coming  often  to  have  these  teeth  extracted. 

Treatment  of  Atrophied  Teeth. 

First  molars.  Such  treatment  of  atrophied  first  molars  as 
will  prevent  the  results  detailed  above,  is  exceedingly  desirable. 
The  treatment  is  required  as  early  as  the  eighth  year,  often  in 
the  seventh.     A  few  cases  may  be  successfully  filled.     Cases 

4b 


26  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

which  promise  good  results  and  iu  which  the  child  can  be  con- 
trolled to  do  this  work,  the  fissures  should  be  properly  prepared 
and  filled  with  gold  at  once  when  discovered.  Generally,  how- 
ever, it  will  be  found  impracticable  to  make  the  proper  prepara- 
tion and  the  fillings  at  so  early  an  age  because  of  failure  to  con- 
trol the  child.  As  the  rule,  it  would  be  necessary  to  do  this  dur- 
ing the  seventh  or  eighth  year.  A  large  proportion  of  these 
cases  are  too  badly  decayed  before  the  ninth  year  for  filling,  and 
many  of  them  are  decayed  to  exposure  of  the  pulp,  or  the  occlusal 
surface  is  lost  during  the  seventh  or  eighth  year.  Ordinarily 
they  will  be  seen  first  by  the  dentist  when  the  child  is  brought  for 
consultation  I'egarding  the  deformity  of  the  incisor  teeth,  the 
parents  not  having  noticed  the  deformity  of  the  first  molars. 
Even  at  that  time,  in  many  cases,  the  first  molars  will  be  found 
badly  decayed.  This  very  early  appearance  of  caries  in  these 
cases,  and  the  fact  that  the  pulp  of  the  tooth  is  so  often  exposed 
by  a  decay  that  seems  not  to  be  very  deep,  greatly  increases  the 
difficulty  of  treatment. 

When  the  teeth  can  be  seen  very  early,  or  as  soon  as  they 
have  come  through  the  gums,  and  the  occlusal  surfaces  are  found 
badly  deformed,  showing  many  wrinkles  and  deep  fissures,  it 
is  generally  best  to  grind  away  any  small,  sharp  spiculae  of 
cusps  that  are  liable  to  be  broken  in  chewing  food.  Then,  if 
decay  has  not  actually  begun  in  the  fissures,  these  may  be  dried 
out  and  filled  at  once  with  oxyphosphate  of  copper  cement  with- 
out further  preparation.  Often  such  a  course  will  be  necessary 
in  order  to  do  anything  that  will  be  of  service  to  the  child.  A 
good  article  of  this  cement  is  often  very  adhesive  and  will  remain 
for  a  considerable  time  in  a  very  slight  crevice  and  seems  to 
prevent  the  beginning  of  decay.  In  the  deeper  fissures  in  which 
decay  starts  earliest,  it  will  do  excellent  temporary  service. 
When  decay  has  made  some  progress  the  softened  material 
should,  if  possible,  be  removed  after  breaking  away  any 
undermined  enamel,  and  the  cavity  thus  formed  filled  with  oxy- 
phosphate of  copper.  In  many  of  these  cases  even  this  slight 
preparation  will  appear  impracticable.  The  child  will  need 
encouragement  and  a  gradual  building  up  of  confidence,  and  often 
much  may  be  done  by  making  the  filling  without  any  excavation 
that  will  cause  pain  and  defer  the  excavation  to  another  time. 
Such  fillings  should  be  examined  after  a  month  to  note  the  result 
and,  when  necessarj%  something  further  may  be  done.  Many 
children  will  become  proud  of  what  they  can  do  in  the  dental 
chair  and  after  a  few  visits  will  bear  a  considerable  operation. 


ATROPHY    OF    THE    TEETH.  27 

In  any  case,  oxyphospliate  fillings  should  be  examined  as  often 
as  once  in  three  months  to  see  that  they  are  doing  well  and  to 
mend  up  any  failures.  In  this  way  these  teeth  can  often  be 
tided  along  and  serious  decay  prevented  until  such  time  as  per- 
manent operations  can  be  made. 

Those  cases  in  which  the  condition  of  the  occlusal  surface 
is  still  worse  and  in  which  decay  seems  to  start  in  spite  of  the 
effort  to  prevent  it  in  this  way,  a  gold  cap  may  be  made  to  cover 
in  the  entire  exposed  part  of  the  crown.  After  grinding  down  the 
more  prominent  points  that  will  cause  the  cap  to  interfere  with 
the  occlusion,  an  impression  should  be  taken  in  modeling  com- 
pound. This  may  be  taken  in  the  little  impression  cups  used 
in  crown  work.  Often  these  may  be  cut  down  considerably  to 
decrease  their  bulk,  which,  in  the  mouth  of  the  little  child,  is  a 
serious  objection.  The  arrangement  should  be  made  to  obtain 
a  very  sharp  impression  very  quickly.  To  this  end,  the  softened 
modeling  compoimd  should  be  placed  in  the  cold  cup  and  allowed 
to  partially  stiffen.  Then  the  surface  should  be  warmed  quickly 
over  a  Bunsen  or  alcohol  flame  and  quickly  conveyed  into  the 
mouth  and  pressed  over  the  tooth.  It  should  be  held  in  position 
for  several  minutes,  if  practicable,  so  that  the  mass  may  become 
hard  enough  not  to  be  drawn  or  marred  in  its  removal.  By  this 
plan  a  very  sharp  impression  can  be  obtained.  From  this  a  gold 
cap  can  be  formed  to  cover  in  the  occlusal  surface  of  the  tooth 
and  maj^  be  cemented  in  place.  There  should  be  no  attempt 
to  make  a  full  gold  shell  crown.  It  should  only  overlap  the  axial 
surfaces  sufficiently  to  hold  it  in  place.  A  renewal  later,  when 
it  can  be  slipped  further  over  the  tooth,  shoiild  be  expected  in 
many  of  the  cases.  The  gum  will  cover  much  of  the  crown  at 
the  age  of  seven  or  eight  years,  and  the  child  will  be  very  sensi- 
tive about  any  pushing  away  of  the  soft  tissues. 

Sometimes  it  will  be  impossible  to  place  these  without  some 
interference  with  the  occlusion.  This  will  not  be  of  much  impor- 
tance if  the  interference  is  not  very  considerable,  for  the  occlu- 
sion is  quickly  accommodated  by  movement  of  the  teeth  in  early 
childhood.  Special  attention  should  be  given  to  the  intercusp- 
ing  of  these  caps  that  the  teeth  may  not  be  caused  to  slide  out 
of  position  during  the  process  of  shedding  the  deciduous  teeth. 
(See  article  on  the  intercusping  of  the  first  molars  in  Manage- 
ment of  Children's  Teeth.)  These  caps  can  often  be  improved 
by  filling  in  deep  grooves  and  by  some  broadening  of  the  occlusal 
surfaces  of  the  models  before  they  are  swedged;  and,  in  doing 
this,  the  intercusping  can  be  studied  and  arranged.     Generally 


28  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE    TEETH. 

the  crowns  will  have  to  be  made  rather  flat  and  the  cusps  short 
in  order  to  prevent  raising  the  bite  excessively,  especially  if 
this  must  be  done  after  the  teeth  have  come  into  full  occlusion. 

These  caps  should  be  regarded  as  a  temporary  expedient. 
When  the  child  is  older  the  time  will  come  when  the  teeth  may 
be  permanently  filled  with  gold  and  the  repair  made  permanent. 
In  the  bad  cases,  requiring  considerable  gold  building,  this 
should  not  be  attempted  before  the  person  is  eighteen  or  twenty 
years  old.  The  pulp  is  so  near  the  occlusal  surface  that  it  will 
be  much  endangered  if  this  building  of  gold  with  sufficient 
anchorage  be  undertaken  earlier.  In  the  meantime  a  careful 
guard  must  be  kept  to  see  that  decay  does  not  begin  on  the  axial 
surfaces  along  the  gingival  margins  of  these  caps  and  cause 
trouble.  Caps  put  on  in  this  way  at  from  seven  to  ten  years  of 
age,  even  if  they  reach  fully  under  the  free  margin  of  the  gum  at 
the  time  they  are  placed,  will  be  some  distance  from  the  free 
margin  of  the  gum  after  a  few  years.  If  decay  occurs,  a  new  cap 
may  be  made  to  cover  it. 

It  is  the  duty  of  every  dentist  having  families  in  his  charge 
to  see  to  it  carefully  that  these  atrophied  molars  are  taken  care 
of  in  this  way,  or  some  similar  way,  very  early.  After  the  patient 
has  grown  older  and  the  teeth  have  come  further  through  the 
gum,  other  devices  may  be  used  if  thought  necessary. 

Some  cases  may  be  successfully  treated  by  grinding  away 
a  considerable  part  of  the  injured  enamel  and  thus  gain  a  smooth 
surface  that  will  be  kept  clean  by  the  excursions  of  food  in  masti- 
cation. This  may  often  be  employed  advantageously  after  con- 
siderable decay  has  occurred.  For  little  children  it  should  be 
done  little  by  little,  having  them  come  to  the  office  frequently  for 
this  purpose.  Particularly  this  should  be  the  case  if  any  sensi- 
tiveness has  developed. 

Incisors  and  cuspids.  The  treatment  of  incisors  and  cuspids 
should  be  along  different  lines.  In  a  very  large  proportion  of 
these  cases,  no  treatment  whatever  is  necessary,  for  these  teeth 
are  not  much  inclined  to  decay  because  of  atrophy.  Yet,  some- 
times decay  does  occur,  and  if  the  atrophy  is  confined  pretty 
closely  to  the  incisal  edge,  it  may  usually  be  treated  by  grinding 
away.  Often  the  atrophied  portion  may  be  ground  away  so  that 
the  tooth  will  look  fairly  well.  It  will  be  a  little  bit  short,  but 
the  inclination  will  be  to  protrude  further  through  the  gums 
and  increase  its  length  in  that  way.  If  necessary,  other  teeth 
in  the  neighborhood  may  be  ground  also,  shortening  them  a  little, 
and  in  this  way  the  esthetic  in  appearance  may  be  satisfied. 


ATROPHY   OF    THE    TEETH.  29 

removing  much,  sometimes  all,  of  the  atrophied  portion.  Often 
teeth  that  are  marked  by  grooves  may  be  made  to  look  very 
well  by  grinding  the  enamel  smooth  and  level,  making  in  this 
way  a  fairly  good  tooth  form,  being  careful,  however,  not  to 
expose  the  dentin  on  the  labial  surface.  Exposure  of  the  dentin 
on  the  cutting  edge  is  not  very  objectionable. 

Frequently  much  harm  is  done  to  these  atrophied  teeth  by 
attempting  to  fill  blackened  pits.  At  the  points  where  these 
occur,  the  teeth  are  often  very  thin  and  an  injudicious  effort 
to  excavate  results  in  cutting  through  to  the  lingual  surface, 
and  after  removing  perhaps  considerable  material  to  gain  the 
proper  anchorage,  the  operator  finds  the  incisal  portion  of  the 
tooth  too  weak  to  stand.  No  filling  should  be  made  for  the  pur- 
pose of  closing  up  blackened  pits,  unless  it  is  first  found  that 
there  is  abundant  tooth  material  for  strength  after  the  excava- 
tion has  been  made.  Also  it  must  be  remembered  that  the  pulps 
of  these  atrophied  incisors  are  very  near  the  incisal  edge  as  a 
rule,  and  exposure  of  this  organ  in  the  excavation  is  very  liable 
to  occur. 

Incisor  teeth  that  are  very  badly  atrophied  so  as  to  give 
a  bad  appearance,  should  not  be  treated  hurriedly.  They  should 
be  tided  along  until  such  time  as  the  pulps  may  be  removed,  not 
only  with  safety,  but  that  the  roots  may  be  filled  in  such  a  manner 
that  they  may  do  service  for  the  lifetime.  If  they  can  be  kept 
in  position  without  other  treatment  than  that  intended  as  tem- 
porary, until  the  patient  is  eighteen  to  twenty  years  old,  it  is 
very  much  better  that  it  should  be  done.  Then  the  crowns  can 
be  cut  away  and  artificial  crowns  put  on  with  the  best  prospect 
for  future  service.  Certainly  no  crowning  operations  should  be 
undertaken  in  these  teeth  before  the  patient  is  sixteen  years  old, 
and  eighteen  to  twenty  is  very  much  better. 

Long  observation  of  the  removal  of  the  pulps  and  filling 
roots  for  young  people  shows  that  these  teeth  do  not  do  well. 
It  is  true  that  we  can  remove  the  pulps  and  fill  the  roots  of  the 
central  incisors  at  twelve  years  old  in  very  many  cases  with 
results  that,  within  the  first  year  or  two,  seem  perfect,  but  it  is 
also  true  that  these  teeth  tend  to  break  down,  the  roots  to  split, 
or  some  catastrophe  is  very  likely  to  happen  to  them  before  the 
patient  is  twenty-five  years  old,  and  the  teeth  are  lost. 

Many  of  them  suppurate  after  they  have  been  apparently 
in  perfect  health  for  several  years  after  the  root  filling  has  been 
made.  All  of  these  considerations  unite  to  advise  that  the 
removal  of  crowns  for  the  purpose  of  placing  artificial  crowns 


30  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

be  delayed  as  long  as  possible.  The  roots  of  these  teeth  are  just 
as  good  for  the  purpose  of  artificial  crowns  as  the  roots  of  fully 
developed  teeth;  in  fact,  all  of  that  portion  of  the  tooth  root-wise 
of  the  atrophied  part  is  normally  developed  as  a  rule.  In  all 
of  this  work  there  is  an  opportunity  for  the  exercise  of  great 
skill  and  taste  in  bringing  about  excellent  esthetic  effects. 

Pits  in  the  Enamel. 

Pits  in  the  enamel  are  a  common  accompaniment  of  atrophy 
of  the  teeth,  but  not  in  any  way  a  necessary  part  of  it,  as  is 
shown  by  the  many  cases  of  even  the  severer  injuries  in  which 
they  are  absent.  Indeed,  in  reckoning  up  the  cases  coming  under 
my  notice,  enamel  pits  seem  not  to  have  been  present  in  more 
than  one-fourth  of  them.  Further,  these  enamel  pits  occur  in 
teeth  that  are  otherwise  normal.  It  is  not  very  rare  to  find  a 
single  pit  in  the  enamel  of  some  one  tooth  of  an  otherwise  per- 
fect set  of  teeth.  In  exposing  such  pits  by  cutting  sections,  the 
same  histological  characters  are  found  as  shown  by  the  pits 
accompanying  atrophy.  They  mark  an  imperfection,  or  partial 
failure,  in  the  development  of  the  enamel  rods,  confined  to  a 
small  area,  usually  round,  and  evidently  are  most  apt  to  occur 
in  cases  where  there  has  been  some  marked  difficulty  in  enamel 
development,  resulting  in  atrophy.  Hence,  they  are  a  frequent 
accompaniment  of  atrophy.  Not  infrequently,  the  rows  of  pits 
in  the  enamel  are  the  only  signs  of  injury  to  the  teeth  as  a  result 
of  an  illness.  In  this  case  the  rows  of  pits  form  zones  on  the 
parts  of  the  teeth  contemporaneous  in  development,  as  one  of 
the  expressions  of  atrophy.  When  they  occur  in  the  absence  of 
atrophy,  they  may  occur  in  any  part  of  the  enamel,  showing  no 
especial  preference  as  to  teeth  or  locality  on  any  tooth. 

The  pit  marks  the  failure  of  development  of  the  enamel  rods 
at  a  point,  leaving  a  hole  of  more  or  less  depth.  This  is  generally 
filled,  or  party  filled,  with  an  amorphous  material,  dark  in  color, 
varying  from  a  yellowish  hue  to  a  deep  black.  I  have  never  yet 
made  a  section  of  one  of  these  in  which  the  dentin  was  exposed, 
though  some  are  as  deep  or  deeper  than  the  normal  thickness  of 
the  enamel.  In  all  of  these  cases  of  very  deep  pits  there  is  a 
depression  in  the  dento-enamel  junction,  as  shown  in  Figure  34, 
and  a  lining  of  enamel,  in  which  the  enamel  rods  are  arranged 
in  a  segment  of  a  whorl,  all  pointing  to  the  center  like  the  spokes 
of  a  wheel,  in  the  bottom  of  the  i)it.  When  the  enamel  rods 
forming  these  whorls  have  grown  about  a  certain  length,  growth 
ceases,  and  an  opening  is  left,  and  this  may  extend  as  an  o])en 


ATROPHY   OF    THE    TEETH.  31 

pit  to  the  outer  surface  of  the  enamel,  leaving  an  opening  the 
full  depth.  Or  this  may  be  filled  in  part  by  a  dark  material 
not  resembling  enamel.  Or,  again,  the  surrounding  enamel  rods 
may  close  over  it,  partially  or  completely  obscuring  the  pit,  so 
as  to  form  a  smooth  enamel  surface  over  it.  In  Dr.  Callow's 
case,  described  later,  the  deformity  consists  mostly  in  numerous 
examples  of  these  whorls,  many  of  them  extending  deeply  into 
the  dentin.  In  Figure  .'>4  the  enamel  rods  close  over  the  whorl 
of  rods  imperfectly,  but  leave  a  ragged  pit  in  the  surface  of  the 
enamel.  That  these  whorls  are  sometimes  closed  over  so  as  to 
give  a  perfect  enamel  surface,  is  shown  in  Figure  42,  from  the 
occlusal  surface  of  a  bicuspid  from  Dr.  Callow's  case.  These 
definite  whorls  are  at  the  dento-enamel  junction,  or  actually 
partly  within  the  dentin.  But  many  pits  are  formed  within  the 
usual  thickness  of  the  enamel  without  disturbance  of  the  line 
of  the  dento-enamel  junction,  as  shown  in  Figure  35.  In  most 
of  these  cases  there  is  much  disturbance  of  the  direction  of  the 
enamel  rods  in  the  immediate  neighborhood  as  the  rule.  In  some 
there  seems  to  be  a  failure  of  the  enamel  organ  to  perform  its 
function  of  rod  formation  at  the  particular  spot.  In  and  about 
many  of  these  pits  there  is  deep  discoloration.  Many  times  the 
dark  color  is  confined  to  the  pit  itself,  which  is  partially  filled 
with  a  substance  strongly  resembling  the  chittinous  covering  of 
insects  in  appearance  and  in  which  no  enamel  rods  can  be  made 
out.  In  other  cases  the  dark  color  extends  broadly  in,  or  among, 
the  enamel  rods  about  the  pit. 

In  these  pits  the  disturbance  follows  the  general  direction 
of  the  enamel  rods  in  the  locality.  This  is  as  true  of  the  pits 
that  accompany  atrophy  as  those  that  occur  without  atrophy. 
In  this  the  pit  is  distinctly  different  from  the  other  injuries  to 
the  enamel  in  atrophy,  for  these  as  uniformly  follow  the  lines  of 
Ritzeus,  i.  e.,  the  lines  of  accretion. 

I  have  been  unable  to  form  any  idea  of  the  pathology  con- 
cerned in  the  formation  of  these  pits.  Their  special  prevalence 
in  atrophy  cases  indicates  that  they  are  due  to  disturbances  of 
nutrition.  They  consist  essentially  in  a  failure  in  the  formation 
of  enamel  rods.  But  such  remarkable  disturbances  as  those 
shown  in  Dr.  Callow's  case,  described  next,  indicate  that  there 
may  be  some  other  pathological  element  not  yet  understood. 
Histologically,  they  seem  to  be  a  very  distinct  form  of  atrophy. 
The  rule  is  that  these  pits  need  no  treatment.  They  rarely  decay, 
but  as  there  is  a  slight  opening  and  the  tissue  is  often  black 
or  dark  colored  for  a  little  bit  around  it,  dentists  frequently 


32  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE    TEETH. 

cut  them  out  and  make  fillings.  There  is  no  reason  for  doing 
this  unless  softening  has  occurred,  or  in  other  words,  unless 
decay  has  actually  begun.  Of  course  in  that  case  the  filling 
is  the  proper  procedure,  but  not  otherwise. 

Other  Deformities  op  the  Ekamel. 

In  examining  the  teeth  of  many  people,  other  deformities 
of  the  enamel  than  atrophy  and  the  pits  above  described  are 
occasionally  met.  It  is  desirable  that  these  be  distinguished 
and  separated  from  typical  atrophy.  Generally,  this  is  easy 
if  we  keep  the  typical  forms  of  atrophy  in  mind.  Atrophy,  due 
to  suspension  of  nutrition,  affects  certain  parts  of  certain  teeth, 
following  the  lines  of  contemporaneous  development,  and  when 
this  is  seen  in  any  one  tooth,  certain  parts  of  certain  other  teeth 
are  marked  and  all  others  have  escaped.  Therefore,  if  we  find 
a  ease  in  which  a  certain  part  of  each  tooth  of  the  whole  set  is 
pitted  and  rough,  or  grooved,  the  injury  or  deformity  not  fol- 
lowing the  lines  of  contemporaneous  development,  we  have 
found  another  condition  entirely  and  should  separate  it  sharply 
from  the  form  of  atrophy  above  described.  How  many  such 
cases  have  been  confounded  with  atrophy  in  the  past  that  have 
no  histological  or  causal  relation  to  it  can  not  now  be  told.  That 
some  have,  there  is  no  longer  room  for  doubt.  I  have  collected 
a  number  of  such  eases.  I  shall  describe  only  some  of  the  most 
notable  cases  coming  under  my  observation.  I  shall  not  try  to 
group  these  into  special  kinds  of  deformities,  for  the  reason  that 
I  have  not  studied  a  sufficient  number  to  arrive  at  general  con- 
clusions. 

general  deformity  of  the  enamel. 

I  received  from  Dr.  J.  E.  Callow,  of  Antigo,  Wisconsin, 
sixteen  teeth  removed  by  him  for  a  young  woman  who  applied 
to  him  for  treatment.  They  included  incisors,  cuspids,  bicuspids 
and  molars.  The  condition  of  these  teeth,  as  indicated  by  their 
outward  appearance,  is  very  fairly  shown  in  the  photograph, 
Figure  36,  of  a  cuspid,  bicuspid  and  molar.  All  of  the  others 
were  similar.  Examination  of  these  teeth  showed  that  the  injury 
to,  or  the  deformity  of,  the  enamel  had  no  relation  to  contem- 
poraneous lines  of  calcification.  Histologically,  although  there 
were  scattered  interglobular  spaces,  there  were  no  markings  in 
the  dentin  that  bore  any  relation  to  those  that  occur  in  atrophy. 
Either  of  these  were  sufficient  to  distinguish  it  as  something 
different  from  atrophy.     In  all  of  the  teeth,  from  incisors  to 


Fia.  34.     A  photomicrograph  of  a  deep  pit  in  the  enamel,  beginning  in  a  whorl  of  enamel  rods  at 
the  dento-enamel  junction.     Much  of  the  pit  is  filled  with  amorphous  material. 


Fio.  35. 


Fig.  35.  A  photomicrograph  of  a  pit  in  the  enamel  beginning  in  the  midst  of  enamel  tissues, 
showing  a  failure  of  the  development  of  enamel  rods.  The  pit  is  nearly  filled  with  amorphous  mate- 
rial, very  dark  in  color,  and  much  of  the  enamel  in  the  neighborhood  is  discolored. 


Fig.  36. 


Fio.  36.  A  cuspid,  a  bicuspid  and  a  molar  tooth  from  Doctor  Callow's  case.  These  are  fair  rep- 
resentatives of  the  appearance  of  the  other  teeth  from  the  same  mouth,  from  several  of  which  sections 
were  cut. 


Fig.  37. 


Fig.  37.  Portion  of  buccal  enamel  from  near  the  buccal  cusp  of  a  second  molar  from  Doctor 
Callow's  case.  Note  that  the  den  to -en  am  el  junction,  which  shows  plainly  at  the  right  in  the  picture,  is 
completely  broken  into  small  whorls  in  all  of  the  left  portion.  While  there  is  a  portion  of  regularly 
formed  enamel  on  the  right,  all  of  the  enamel  on  the  left  portion  is  broken  or  twisted  out  of  semblance 
of  ordinary  enamel.  Also  note  the  tubelike  opening  to  the  surface  near  the  middle  of  the  illustration. 
These  features  are  found  to  be  repeated  with  differences  of  detail  in  the  other  illustrations. 


''-*?»> 


Fig.   38.     Portion  of    enamel   from   near   gingival    line   on    the   buccal   surface  of  a   second   molar 
from  Doctor  Callow's  case. 

Fig.  30.    From  the  buccal  surface  of  a  first  molar,  near  the  buccal  cusp,  from  Doctor  Callow's  case. 


■s       -       ,^ 


Jii|lw/'„V'  ''\ 


I'iG.     40. 


Fig.  40.     Buccal  cusp  of  a  second  bicuspid,  from  Doctor  Callow's  case. 


# 


FiQ.   41. 


l''iG.    41.     Distoition  of  cnann_'l  on  lingual  mrface  of  a  bicusjiul,  fioni  Dr.  Callow's  oase. 


/.?::'r=/^;s 


WW 


m 


■  ♦' 


^|i 


# 


V 


Fig.  42.     Enamel  pits  closed  over,  leaving  cavities,  over  which  a  fairly  smooth  enamel  is  formed. 
Occlusal  surface  of  a  bicuspid,  from  Doctor  Callow's  case. 


Fifi.    4.{.      A   bit    of  riiani.'l    iippearing   in   s^i'clion    u^;    an    island    in    thu    midst   of   the    dentin    in    a 
bicuspid,   liiitn   Doctor  Callow's  case. 


AJ'i^- 


Fio.   44. 


Fui.   4r. 


Fig.  44.  Knamel  from  near  the  cusps  of  a  tooth  in  Doctor  Prunty's  case,  showing  the  enamel  rods 
breaking  into  bundles  which  end  in  spicule.  This  enamel  had  no  cementing  substance  between  the 
enamel  rods.     Its  color  was  a  dead  paper-white. 

Fig.  45.  A  scrap  from  one  of  the  best  parts  of  enamel  fovmd  in  Doctor  Prunty's  case,  showing  the 
rods  to  be  without  cementing  substance  between  them. 


Fig.  46. 


Fig.  46.  White  spot  in  the  cnunit'l  oi  uii  uthtruisc  iKHiiiiil  imitli.  In  the  uliitp  area  the  enann^l 
rods  have  no  conienting'  suhslancf  hi'lui-m  thmi.  Tlicy  ha\i-  a  cxciiny:  on  the  surfate,  hciwcvrr.  that 
has  the  usual    har<l  ^\a.'/.e  common  !<»  the  suiiati-  of  nmnial   rnanicl.      This  is  Naysmilh's  iinMnhrane. 


j=e»K»_ 


Fio.  47. 


Fig.    47.     White  spot    in   enamel.      At    the   right,    little   bundles   of   rods   are  seen   to    be   without 
cementing  substance  between  them. 


ATROPHY    OF    THE    TEETH.  33 

third  molars,  the  deformity  was  greatest  on  the  axial  surfaces 
and  least  on  the  cutting  edges  and  cusps.  The  surfaces  were 
extremely  rough  and  uneven,  presenting  sharp  apiculai  or  knobs 
and  deep  pits  in  the  utmost  irregularity  of  form.  Over  some  of 
the  cusps  the  enamel  seemed  to  be  normally  thick,  but  did  not 
have  the  smooth  glazed  surface  of  normal  enamel.  Only  occa- 
sionally a  small  area  would  show  the  normal  smoothness.  In 
most  of  the  teeth  the  enamel  assumed  a  normal  appearance  sud- 
denly near  the  gingival  line,  and  this  normal  part  generally 
encircled  the  tooth,  joining  the  cementum  in  a  normal  gingival 
line. 

Figures  37,  38,  39,  40,  41  and  42  are  photomicrographs  show- 
ing the  histological  characters  of  the  enamel.  In  most  of  its 
parts  the  dento-enamel  junction  is  lost  in  a  wild  jumble  of  cir- 
cular whorls  or  protrusions  of  enamel  into  the  dentin.  Quite 
a  number  of  these  whorls  are  hollow  and  empty,  while  some  are 
filled  with  amorphous  material,  but  all  of  these,  without  excep- 
tion, are  lined  with  enamel,  usually  in  the  form  of  segments  of 
whorls,  as  these  are  found  in  the  bottom  of  other  enamel  pits. 
In  some  this  lining  is  veiy  thin.  Some  of  these  hollows  commu- 
nicate with  the  surface  by  small  tubelike  openings,  forming  very 
deep  pits.  Figures  37,  39,  while  others  seem  to  be  closed  on  all 
sides,  Figures  37,  40,  42.  In  occasional  patches,  even  where  the 
enamel  began  in  these  whorls  along  the  dento-enamel  junction, 
the  rods  to  either  side  straightened  up  and  closed  over  them  into 
a  fairly  well  formed  enamel,  as  shown  in  Figure  42,  from  the 
occlusal  surface  of  a  bicuspid.  Still,  most  of  the  formed  enamel 
is  a  wild,  twisting,  curving  and  bundling  of  enamel  rods.  With 
all  of  this  the  enamel  formed  seemed  to  be  of  normal  hardness 
in  every  part.  In  a  considerable  number  of  places  the  enamel 
is  plunged  deeply  into  the  dentin  in  long  prolongations  that  were 
too  large  and  long  to  permit  photographing  with  any  lens  with 
sufficient  amplification  to  enable  the  structure  to  be  distinguished. 
Figure  43  shows  a  little  part  of  one  of  these  appearing  as  an 
island,  midway  between  the  cementum  and  the  pulp  canal,  con- 
siderably root-wise  of  the  gingival  line.  This  is  not  an  actual 
island  of  enamel,  however,  for  it  was  traced  as  a  part  of  a  very 
long  projection  from  the  dento-enamel  junction  near  one  of  the 
cusps  of  the  tooth.  Fortunately,  I  used  my  sectioning  machine 
and  had  cut  these  teeth  in  very  thin  slices,  so  that  I  was  able  to 
follow  such  a  growth  through  several  sections.  In  general,  the 
pictures  given  show  the  characters  of  the  departure  from  the 
normal  very  much  better  than  it  can  be  portrayed  in  words.    In 


34  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE   TEETH. 

this  case  I  could  get  no  indication  of  any  other  abnormal  con- 
dition of  the  patient.  She  seems  to  have  been  otherwise  a  normal 
and  healthy  girl. 

Many  of  the  teeth  were  badly  decayed  and  it  is  represented 
that  all  of  them,  whether  decayed  or  not,  were  abnormally  sensi- 
tive to  sweets,  heat  and  cold,  and  to  acid  fruits.  Also,  that  this 
condition  of  sensitiveness  had  been  persistent  since  the  eruption 
of  the  teeth.  This  sensitiveness  was  so  continuous  and  severe 
that  it  led  finally  to  the  removal  of  all  of  the  teeth  for  relief. 
In  all  of  my  observation  this  unique  case  stands  alone.  Consid- 
ered as  a  whole,  I  have  studied  nothing  else  like  it.  I  have,  how- 
ever, observed  in  the  mouth  a  number  of  cases  that  may  have 
been  of  this  character.  The  definiteness  of  the  deformity  and 
the  perfectness  with  which  this  definite  histological  character 
was  repeated  in  each  tooth  examined,  indicates  that  it  is  a 
deformity  to  which  the  teeth  are  liable.  This  is  emphasized  by 
the  frequent  observation  of  the  tendency  seen  along  the  line  of 
the  dento-enamel  junction  to  form  scallops  and  whorls  in  teeth 
otherwise  normal.  But  I  know  nothing  of  the  conditions  leading 
to  this  kind  of  deformity. 

Dr.  M.  C.  Smith,  of  Lynn,  Massachusetts,  presented  casts 
of  a  case  at  Buffalo,  at  the  meeting  of  the  National  Dental  Asso- 
ciation, 1905,  which  seemed  to  me  to  be  of  the  same  character. 
When  I  examined  these  models,  no  teeth  had  been  extracted  and 
no  opportunity  presented  for  a  histological  study.  Dr.  Smith's 
case  presented  the  same  difiBculty  as  to  sensitiveness. 

White  Spots  in  the  Enamel. 

White  enamel  is  seen  in  occasional  white  or  ashy  gray  spots 
occurring  in  the  enamel  of  teeth  otherwise  normal  in  color  and 
form.  These  white  spots  are  usually  small  and  are  covered  with 
the  ordinary  glazed  surface  of  the  enamel,  so  that  an  exploring 
tine  will  glide  over  them  the  same  as  over  the  perfect  enamel. 
If,  however,  the  spots  are  large,  this  glazed  surface  fails  to  cover 
the  central  portion,  being  projected  but  part  way  from  the  mar- 
gin toward  the  center.  In  that  case,  the  central  area  is  rough, 
and  an  exploring  tine  enters  the  enamel  without  difficulty.  Such 
spots  as  these  latter  are  rare.  Sometimes  such  a  spot  shows 
discoloration  about  its  central  portion  or  radiating  through  it 
in  irregular  lines  or  blotches.  The  smaller  white  spots  covered 
with  the  glazed  membrane  are  common  in  any  great  school  clinic 
where  large  niunbers  of  persons  are  present  for  dental  oper- 
ations 


ATBOPHY   OP   THE   TEETH.  35 

A  histological  examination  of  these  shows  the  enamel  rods 
to  be  normal  in  their  formation  and  continuous  with  the  rods 
deeper  in  the  enamel,  which  is  altogether  normal  in  form  and 
color.  Generally  the  smaller  white  spots  that  appear  on  the  sur- 
face of  the  enamel  do  not  extend  through  its  thickness.  It  often 
ends  abruptly  in  a  line  following  the  incremental  lines  of  enamel 
formation,  i.  e.,  the  lines  of  Ritzeus,  as  seen  in  Figures  46,  47. 
In  the  area  of  the  white  spot  there  is  no  cementing  substance 
between  the  enamel  rods.  This  is  the  histological  characteristic 
of  all  of  these  white  spots  that  I  have  yet  examined.  This  is, 
therefore,  an  atrophy  affecting  the  formation  of  the  cementing 
substance  between  the  enamel  rods  the  same  as  certain  of  the 
pits  in  the  enamel  are  an  atrophy  of  the  enamel  rods.  While 
white  enamel  usually  occurs  in  small  spots  occupying  but  a  small 
amount  of  the  surface  of  a  tooth,  they  are  occasionally  much 
larger,  and  I  shall  relate  cases  in  which  all  of  the  enamel  of  all 
of  the  teeth  of  the  person  was  of  this  character. 

WHITE    ENAMEL. 

I  received  fourteen  teeth  from  Dr.  D.  J.  McMillen,  of  Kansas 
City,  which  had  been  extracted  by  Dr.  John  Prunty,  of  Boyd, 
Texas,  for  one  patient,  all  of  which  were  deformed  in  what,  from 
macroscopic  examination,  seemed  a  similar  manner  to  that 
described  in  Dr.  Callow's  ease.  The  teeth  were  very  dirty  with 
blood  stains  and  from  being  handled,  which  obscured  some  of 
their  most  notable  characters.  But  a  closer  examination  showed 
the  enamel  to  be  soft.  I  found  that  it  could  easily  be  picked 
to  pieces,  and  evidently  much  of  it  had  been  lost  in  this  way  since 
the  teeth  were  extracted.  The  axial  surfaces  were  made  up  of 
irregularly  formed  spiculae  that  rendered  them  extremely  rough. 
Many  of  these  had  been  broken,  so  much  so,  indeed,  that  it  was 
with  some  difficulty  that  I  was  able  to  get  sections  showing  the 
condition  at  the  time  the  teeth  were  extracted. 

When  I  came  to  the  making  of  sections  of  these,  I  found  the 
enamel  white  through  its  entire  thickness,  not  the  white  bluish 
color  of  enamel,  but  the  white  color  of  unglazed  white  paper. 
The  enamel  had  seemed  so  frail  that  I  had  soaked  the  teeth  in 
thin  balsam  and  then  thoroughly  dried  them,  in  order  to  retain 
the  spiculfe  of  enamel.  Afterward  I  was  sorry  that  I  had  not 
used  shellac  for  this  purpose,  for  in  some  of  my  sections  these 
spiculjE  floated  about  in  the  balsam  in  which  the  mount  was  made, 
as  soon  as  the  slight  amoimt  of  hard  balsam  left  after  grinding 
had  dissolved  in  the  softer  balsam  in  which  it  was  mounted.    The 


36  PATHOLOGY    OP    THE    HARD    TISSUES    OF    THE    TEETH. 

shellac,  which  does  not  dissolve  in  balsam,  would  have  saved  me 
this  chagrin. 

This  case  proved  to  be  something  entirely  different  from 
Dr.  Callow's  case,  histologically.  The  dento-enamel  junction 
was  perfectly  normal  in  all  its  parts.  Next  to  the  dento-enamel 
junction  the  enamel  was  in  perfect  form.  But  after  a  slight 
growth  the  enamel  rods  broke  up  into  bimdles  that  became 
smaller,  and  evidently  these  bundles  had  ended  in  spiculse.  I 
found  none  of  these  that  had  not  been  broken,  though  I  found 
patches  with  the  mucoid  film  formed  in  the  mouth  still  over  them 
after  grinding  the  sections,  which  showed  conclusively  that  the 
spiculas  had  not  been  broken  after  the  teeth  were  extracted. 
Figure  44  shows  this  and  indicates  very  well  the  manner  of  the 
formation  of  these  spiculte.  Evidently  the  finest  of  these  had 
been  broken  after  the  extraction  of  the  teeth.  In  many  places 
very  little  enamel  remained. 

This  enamel  throughout  all  its  parts  was  almost  wholly 
without  the  cementing  substance  between  the  rods.  Figure  45. 
Histologically,  this  was  the  principal  deformity.  I  became  satis- 
fied from  my  examination  that  the  rods  themselves  were  fully 
hai'd,  but  they  were  not  cemented  together  and  broke  apart  with 
the  greatest  ease.  Indeed,  much  of  the  enamel  came  to  pieces 
after  it  was  mounted  and  the  rods  became  scattered  in  the  bal- 
sam. I  have  no  idea  what  controlled  the  formation  of  the  spiculas 
which  constituted  the  principal  outward  deformity.  In  the  mouth 
the  teeth  must  have  had  a  dead  paper-white  appearance. 

I  have  seen  but  one  other  case  presenting  a  general  absence 
of  the  cementing  substance  between  the  enamel  rods.  A  laboring 
man  came  into  the  clinic  at  Northwestern  University  Dental 
School  several  years  ago,  whose  teeth  presented  this  dead  paper- 
white  appearance.  Every  tooth,  and  every  part  of  every  tooth, 
had  this  appearance.  There  was  no  deformity  as  to  form.  But 
Naysmith's  membrane,  which  usually  covers  the  enamel  and 
forms  the  glaze  of  the  surface,  was  absent.  The  teeth  were  of 
usual  size,  of  good  contour,  and  regular  in  the  arch.  He  said 
they  had  always  been  so  and  he  had  been  greatly  annoyed  because 
of  the  attention  their  peculiar  color  attracted.  The  man  was 
twenty-eight  years  old.  There  were  some  points  on  the  cusps 
where  the  enamel  was  worn  enough  to  show  the  dentin,  but  gen- 
erally the  wear  was  not  excessive.  He  said  he  could  chew  food 
as  well  as  anybody.  There  were  three  small  proximal  cavities 
in  the  bicusjjids;  otherwise  the  teeth  were  sound. 

I  partially  excavated  one  of  the  cavities,  found  the  dentin 


ATROPHY   OF    THE   TEETH.  37 

apparently  of  usual  firmness,  but  the  enamel  seemed  to  crumble 
to  pieces  easilJ^  Not  only  the  walls  of  the  cavity  crumbled,  but 
I  could  easily  push  a  sharp  explorer  into  the  enamel  of  other 
teeth  anywhere.  I  took  some  of  the  cuttings  from  the  enamel 
walls  of  the  cavity  well  beyond  the  decayed  area  and  distributed 
them  in  glycerin  under  a  cover-glass,  and  with  the  microscope 
found  well-formed  enamel  rods  that  looked  much  like  those  that 
had  been  separated  by  a  very  weak  acid,  or  those  taken  from 
the  whitened  enamel  in  backward  decays. 

This  condition  of  the  enamel  had  not  rendered  the  teeth 
more  than  ordinarily  liable  to  caries,  as  was  shown  by  the  gen- 
eral soundness  of  the  teeth. 

This  condition  reminded  me  strongly  of  the  white  spots 
so  often  seen  in  the  enamel  of  teeth  that  are  in  the  main  per- 
fectly formed;  and  is  undoubtedly  of  the  same  character.  Fig- 
ures 46,  47.  The  only  difference  seemed  to  be  that  the  usual 
white  spots  seen  are  covered  with  a  very  perfect  glaze,  or  Nay- 
smith's  membrane,  so  that  a  sharp  instrument  will  glide  over 
them.  This  man's  teeth  had  no  such  glazed  surface.  A  sharp 
explorer  would  catch  anywhere  with  very  little  pressure.  In 
fact,  it  would  not  glide  over  the  surface  at  all.  The  teeth  evi- 
dently had  not  a  normal  Naysmith's  membrane.  The  enamel  in 
the  two  cases  seemed  very  similar  to  cutting  instruments.  Since 
writing  the  above  statement,  another  case  has  come  under  my 
observation  in  which  the  incisal  portion  of  the  incisors  and 
cuspids  and  the  occlusal  portion  of  the  bicuspids  and  molars 
were  covered  with  normal  enamel,  but  a  large  part  of  the  axial 
surfaces  were  white  enamel,  much  of  which  lacked  the  glazed 
covering,  or  Naysmith's  membrane.  At  all  points  this  glazed 
membrane  was  projected  to  some  distance  from  the  normal  over 
the  abnormal  enamel. 

These  cases,  taken  together  with  the  frequent  occurrence 
of  white  spots,  led  me  to  the  supposition  that  the  failure  of  the 
cementing  substance  between  the  enamel  rods  is  a  special  form 
of  atrophy  or  abnoi'mality  in  formation  to  which  the  enamel  is 
liable.  The  occurrence  of  this  in  isolated  spots,  which  are  usually 
of  an  ashy  white  color,  is  not  very  uncommon,  but  its  occurrence 
in  the  whole  of  the  enamel  in  the  teeth  of  a  person  is  certainly 
extremely  rare.  I  have  seen  this  in  but  the  two  cases  mentioned, 
in  the  one  with  abnormal  form,  in  the  other  with  normal  form. 

Nothing  seems  to  be  known  of  the  pathology  that  brings 
about  this  condition. 

The  study  of  such  cases  is  of  great  importance,  as  it  may 


38  PATHOLOGY    OF    THE    HABD    TISSUES   OF    THE    TEETH. 

lead  to  further  knowledge  of  the  formation  of  this  tissue.  Cer- 
tainly the  facts  developed  show  that  either  the  functioning  tissue 
or  the  functioning  of  the  tissue  that  forms  the  enamel  rods  is 
so  different  from  that  which  forms  the  cementing  substance 
between  the  rods  that  the  rods  may  be  formed  and  the  cementing 
substance  fail.  Also,  we  have  seen  in  the  illustrations  many 
faihues  of  the  enamel  rods  with  the  space  filled  in  part  with 
something  else  apparently  without  histological  form.  This  some- 
thing may  be  the  cementing  substance  that  should  be  only 
between  the  enamel  rods.  According  to  this  view,  atrophy  of 
the  teeth  presents  three  distinct  phases : 

(1.)  An  atrophy  due  to  a  period  of  malnutrition,  affecting 
those  parts  of  several  teeth  at  the  time  in  process  of  formation. 
This  may  cause  the  failure  of  formation  of  all  parts  of  the  enamel 
and  dentin  in  the  zone  involved,  as  seen  generally  in  atrophied 
teeth. 

(2.)  An  atrophy  of  the  enamel  rods  occurring  in  spots, 
as  seen  in  pits. 

(3.)  An  atrophy  of  the  cementing  substance  between  the 
enamel  rods,  as  seen  in  the  white  spots  often  seen  in  the  enamel, 
and  in  the  enamel  of  the  whole  denture  in  rare  cases,  as  in  the 
two  I  have  described. 

The  first  is  clearly  due  to  a  general  malnutrition  and  is  seen 
only  on  the  parts  of  teeth  contemporaneously  in  formation  at 
a  period  of  illness.  The  second  is  in  part  seen  to  occur  in  process 
of  general  malnutrition,  but  often  occurs  independently  of  this, 
so  far  as  can  now  be  discovered.  The  third,  so  far  as  can  now 
be  seen,  depends  upon  some  condition  of  malnutrition  as  yet 
unknown. 

I  think  Dr.  Callow's  case  should  be  regarded  as  a  deformity, 
not  an  atrophy. 


EROSION    OF    THE   TEETH.  39 


EROSION  OF  THE  TEETH. 

ILLUSTliATIONS :    FIGURES  48-62. 

EROSION  is  a  term  applied  to  a  peculiar  and  very  charac- 
teristic loss  of  substance  of  tiie  teeth,  beginning  in  the 
enamel,  or  upon  its  outer  surface,  and  slowly  working  its  way 
inward  and  spreading,  destroying  and  removing  the  substance 
of  the  tooth  as  it  goes.  At  first  it  presents  no  sjTuptoms  what- 
ever except  this  loss  of  substance,  and  this  looks  like  a  facet 
that  would  be  left  after  grinding  slightly  with  a  very  fine  stone. 
There  is  no  softening  whatever,  but  simply  a  wasting  of  the 
substance,  leaving  a  perfectly  smooth,  polished  surface;  a  sur- 
face so  smooth  and  polished  and  hard  that  an  explorer  passed 
over  it  will  glide  just  as  smoothly  upon  the  eroded  surface  as 
upon  the  enamel  that  is  perfect.  The  facet  first  formed  grad- 
ually deepens  and  widens,  progressing  very  slowly  in  most  cases, 
until  the  enamel  has  been  cut  through.  Then  the  dentin  wastes 
away  in  a  similar  fashion,  and  so  smoothly  that  there  is  no  line 
of  demarkation  between  the  enamel  and  the  dentin.  When  the 
enamel  has  been  penetrated  and  the  dentin  begins  to  be  eroded, 
the  dentin  becomes  very  sensitive.  This  sensitiveness  is  charac- 
teristic of  erosion  if  in  living  teeth.  Teeth  that  have  lost  their 
pulps  may  suffer  from  erosion  in  precisely  the  same  way,  except 
that  in  these  there  will  be  no  sensitiveness. 

Erosion  is  usually  slow  in  its  progress.  The  facets  may 
appear  upon  the  enamel  and  be  seen  for  a  considerable  time 
before  the  enamel  is  penetrated ;  as  a  year,  two  years  or  more. 
It  proceeds  directly  and  steadily,  in  a  large  proportion  of  cases, 
until  the  teeth  are  destroyed,  requiring  from  three  to  ten  years, 
or  even  more,  to  cut  through  and  destroy  a  tooth.  In  other  cases 
the  progress  ceases  spontaneously,  or  the  progress  may  be  inter- 
mittent. 

The  position  of  erosion  is  most  commonly  the  buccal  or 
labial  surfaces  of  the  teeth.  It  is  yet  uncertain  whether  it 
appears  oftenest  upon  the  incisors  or  upon  the  bicuspids  and 
molars.  Sometimes,  however,  it  will  begin  upon  the  proximal 
surfaces,  and  a  few  cases  have  been  observed  upon  the  lingual 
surfaces.    When  it  has  begun  upon  a  surface  of  a  tooth,  the 


40  PATHOLOGY   OF    THE    HAED    TISSUES   OF    THE   TEETH. 

general  rule  is  that  it  does  not  spread  to  other  surfaces,  i.  e.,  if 
it  has  begun  upon  a  labial  surface  there  is  rarely  a  disposition 
to  begin  upon  a  proximal  surface  or  a  lingual  surface,  but  it  will 
be  confined  to  labial  surfaces ;  it  will,  however,  spread  to  other 
labial  surfaces  in  the  neighborhood.  For  instance,  if  it  begins 
upon  a  labial  surface  of  a  central  incisor  —  which  is  not  an 
uncommon  place  of  .beginning  —  it  is  likely  to  spread  to  the 
labial  surface  of  the  other  central  incisor  and  to  the  labial  sur- 
faces of  the  lateral  incisors  and  cuspids,  spreading  from  before 
backward.  If  it  begins  upon  a  first  molar  it  is  liable  to  spread 
to  the  second  and  third  molars  and  to  the  bicuspids,  and  in  most 
of  these  cases  it  will  be  bilateral,  though  occasionally  we  find  it 
unilateral,  not  occurring  upon  the  opposite  side  at  all.  It  may 
also  apparently  spread  from  the  upper  teeth  to  the  lower,  or 
vice  versa,  but  continuing  upon  the  -labial  or  buccal  surfaces, 
not  involving  other  surfaces  of  the  teeth.  If  it  begins  on  proxi- 
mal surfaces,  proximal  surfaces  only  will  be  affected.  But  it 
will  spread  from  tooth  to  tooth.     " 

Diagnosis  of  Erosion. 

One  who  has  carefully  studied  the  conditions  of  the  eroded 
areas  in  a  few  cases  should  have  little  difficulty  in  recognizing 
it  in  any  of  its  forms.  It  should  be  remembered  that  the  form  or 
location  of  the  eroded  area  is  not  distinctive,  for  the  reason  that 
a  great  variety  of  forms  of  area  and  of  location  are  presented. 
The  area  of  eroded  surface  is  always  smooth  and  glossy,  and  a 
sharp  explorer  held  lightly  in  the  fingers  glides  over  it  the  same 
as  over  enamel.  This  distinguishes  erosion  from  beginning 
caries,  but  does  not  distinguish  it  from  abrasion.  All  facets 
occurring  on  the  occlusal  surfaces  of  the  teeth  should  be  regarded 
as  abrasion.  An  examination  should  be  made  that  will  certainly 
exclude  abrasion  from  any  cause  such  as  the  rubbing  of  the  par- 
ticular part  against  another  tooth,  or  rubbing  by  some  artificial 
appliance,  or  the  possible  grinding  by  a  stone  for  any  purpose. 
With  these  excluded,  a  definite  facet  of  any  form  that  is  hard, 
smooth  and  glossy,  is  distinctive  of  erosion.  So  long  as  this  is 
in  the  enamel  only,  it  will  be  the  only  symptom.  A  tooth  with  a 
living  pulp  will  usually  become  sensitive  when  the  dentin  is 
reached,  but  in  cases  that  have  made  much  progress  slowly  in 
dentin,  the  pulps  of  the  teeth  may  become  much  calcified,  and 
the  sensitiveness  will  disappear  on  account  of  the  cutting  off 
of  the  dentinal  fibrils  by  the  calcification.  Obviously  there  will 
be  no  sensitiveness  when  erosion  occurs  in  pulpless  teeth.     In 


EBOSION   OF   THE   TEETH.  41 

case  the  progress  of  erosion  ceases,  the  sensitiveness  of  the 
exposed  dentin  soon  disappears  also,  and  the  dentin  may  become 
discolored.  All  of  these  points  must  be  considered  in  making 
a  diagnosis  of  erosion.  It  will  be  seen  from  the  foregoing  that 
the  one  fact  of  loss  of  substance  without  apparent  mechanical 
cause,  leaving  a  smooth,  glossy  surface  in  dentin,  or  in  enamel, 
or  in  both,  is  the  distinguishing  feature  of  erosion. 

FREQUENCE   OF   EKOSION. 

As  to  frequence  of  occurrence,  erosion  is  rare  as  compared 
with  caries.  Formerly  my  estimate  of  this  was  that  less  than 
one  person  per  thousand  had  erosion  of  their  teeth.  Certainly 
it  was  very  rare  among  my  patients  in  Jacksonville,  Illinois, 
though  I  saw  a  good  many  more  than  my  proper  share  through 
consultations.  For  some  years  after  I  began  teaching  operative 
dentistry,  and  had  opportunity  to  see  the  larger  proportion  of 
the  patients  in  the  clinic,  they  still  were  not  plentiful.  Finally 
I  asked  the  Examiner  to  call  my  attention  to  every  case  he  could 
find  among  those  applying  for  treatment  of  any  kind.  This 
brought  out  so  much  larger  proportion  of  cases  as  to  cause  me 
to  believe  that  many  had  been  overlooked  previously.  It  is  prob- 
able that  very  many  cases  are  overlooked  by  practitioners.  The 
evidence  on  this  point,  however,  remains  very  uncertain. 

Among  the  patients  applying  at  our  clinic,  about  one  per 
cent  of  erosion  is  found.  These  people  are  mostly  friends  of 
the  students.  They  are  not  of  the  very  poor  nor  of  the  wealthy. 
I  find  among  them  erosion  of  every  variety  of  form  that  I  have 
seen  elsewhere,  but  the  roimded  cuts  across  the  teeth  that  tend 
to  become  stationary,  or  cease  to  progress,  seem  to  be  in  the 
majority.  Many  of  these  cases  stop  spontaneously  before  any 
considerable  injury  is  done. 

Erosion  is  much  more  frequent  in  some  certain  classes  of 
people  than  in  others.  Considerable  inquiry  has  been  made 
among  practitioners  regarding  this.  Some  seldom  see  a  case, 
while  others  find  it  very  frequent.  E  specially  those  whose  practice 
is  confined  closely  to  very  well-to-do  people  find  it  most  frequent, 
and  of  a  character  to  do  the  greatest  injury.  One  practitioner 
who  has  a  practice  among  well-to-do  Jewish  people  stated  that 
all  of  his  patients  had  erosion  and  insisted  that  that  was  literally 
correct.  I  then  asked  him  to  take  as  many  casts  as  he  could  for 
me.  Within  a  few  weeks  he  turned  over  so  many  that  his  state- 
ment seemed  to  be  fully  justified.  Not  many  practitioners  can 
make  casts  of  fifty  to  seventy  cases  of  erosion  from  their  own 


42  PATHOLOGY    OF    THE    HAED    TISSUES   OF    THE    TEETH. 

patients  witliin  five  or  six  weeks.  He  gave  me  a  set  of  casts 
from  a  young  man  of  twenty,  his  father,  his  grandfather  and 
his  great-grandfather,  all  taken  the  same  week,  each  showing 
erosion.  This  practitioner  is  fully  convinced  by  his  observations 
among  these  people  that  erosion  is  hereditary.  They  are  prac- 
tically all  descendants  of  a  few  Jewish  families  who  settled  in 
this  country  many  years  ago,  who  have  been  very  much  devoted 
to  the  maintenance  of  their  especial  set.  From  the  descriptions 
first  given  of  erosion  among  these  people,  it  was  expected  that 
much  of  it  would  be  of  one  character  as  to  form,  but  the  examina- 
tion of  the  casts  revealed  a  wide  variety  of  form,  so  much  so 
that  one  could  not  say  that  any  one  particular  form  prevailed 
to  the  exclusion  of  others.  There  were  among  them  two  cases 
of  marked  erosion  of  proximal  surfaces,  cutting  holes  between 
the  bicuspids. 

I  have  also  supposed  from  my  reading  of  the  literature, 
and  especially  from  examination  of  illustrations,  and  from 
inquiry  in  certain  localities  in  this  country  and  abroad,  that  cer- 
tain forms  prevailed  in  certain  localities. 

FORMS    OF    EROSION. 
ILLUSTRATIONS:    FIGURES  48-62. 

DisH-sHAPED  AREAS.  One  of  the  very  common  forms  of 
erosion  we  may  describe  as  a  dish-shaped  excavation,  in  which 
the  center  of  the  eroded  area  is  deepest,  and  from  this  it  rounds 
up  to  the  surface  of  the  enamel  in  every  direction.  This  may 
attack  a  central  incisor  first  and  spread  to  the  teeth  at  either 
side  of  the  tooth  first  attacked,  hardly  ever  exactly  bilateral, 
but  usually  more  extended  on  one  side  of  the  mouth  than  the 
other,  destroying  the  labial  surfaces.  Its  place  of  beginning 
varies  from  the  middle  of  the  gingival  third  to  the  mid-length 
of  the  crown.  Mesio-distally  it  is  usually  about  the  center,  but 
if  there  are  irregularities  in  the  positions  of  the  teeth  it  is  most 
likely  to  begin  on  the  most  prominent  part. 

It  first  forms  a  little  facet  upon  the  enamel,  then  destroys 
more  and  more,  and  finally  passes  through  to  the  dentin,  cutting 
without  any  distinction  whatever  between  the  dentin  and  enamel, 
and  increasing  the  size  of  these  facets  until  the  whole  labial 
surface  has  been  removed,  not  touching  the  proximal  surface, 
and  not  touching  the  inclsal  except  as  it  is  approached  from  the 
labial.  This  form  is  represented  in  Figure  48.  There  is  fre- 
quently an  offshoot  from  the  true  dish  shape  toward  the  incisal. 


Fia.   49. 


Fig.  48.  A  case  of  erosion  occurring  in  the  teeth  of  a  woman  twenty-eight  years  of  age.  These 
are  dish-shaped  areas,  with  projections  toward  the  incisal  edge,  which  are  plainly  seen  in  the  lower 
central  incisors.  Otherwise  it  is  a  case  of  typical  dish-shaped  areas.  A  picture  by  myself  from  the 
same  cast  was  published  in  the  "American  System  of  Dentistry." 

Fig.  49.  The  dish-shaped  areas  complicated  with  recession  of  the  gum.  with  projections  extending 
from  the  dish-shaped  areas  toward  the  incisal  edges,  in  the  upper  teeth.  These  extensions  have  a  very 
characteristic  squareness  of  their  angles.     Patient,  a  man  forty  years  of  age. 


EROSION    OF    THE    TEETH.  43 

particularly  in  the  central  incisors  and  cuspids  above  and  below, 
and  sometimes  in  other  teeth. 

In  examining  the  illustration  it  will  be  noted  that  in  this 
case  the  lower  centrals  present  an  offshoot  which  has  hollowed 
out  the  labial  surface  to  the  cutting  edge.  The  same  has  been 
done  in  the  upper  central  incisors,  but  the  eroded  area  has 
become  so  large  in  these  as  to  almost  obscure  this  feature.  It 
occurs  in  no  other  teeth  in  this  case. 

Figure  49  also  presents  the  dish  shape  of  the  eroded  areas, 
but  in  this  case  it  has  two  complications.  There  is  recession 
of  the  gums  and  the  dish-shaped  portion  of  the  erosion  is  largely 
in  the  cementum,  but  cutting  the  cementum,  enamel  and  dentin 
without  distinction.  This  complication  of  recession  of  the  gums 
with  erosion  is  not  uncommon.  The  erosion  never  passes  under 
the  free  margin  of  the  gum,  and  while  the  gum  may  be  tumified 
or  swollen,  it  is  rare  that  it  ever  laps  over  into  the  eroded  area, 
differing  markedly  from  caries  in  this  respect.  Some  of  the  cases 
look  as  though  the  recession  of  the  gum  may  have  been  caused 
by  the  erosion,  but  we  see  many  cases  of  recession  of  the  gima 
of  similar  character  without  erosion.  We  also  see  many  cases  of 
erosion  cutting  away  the  teeth  very  close  to  the  gum  without 
recession  of  the  gum.  It  would  therefore  seem  that  there  is 
no  causal  relation  between  the  two.  Figure  49  also  has  a  second 
complication  not  so  frequently  seen,  in  the  squared-out  projec- 
tions toward  the  incisal  from  the  dish-shaped  portion  which 
were  noted  in  Figure  48.  In  this  case  the  progress,  however, 
has  been  much  less  and  these  curious  projections  are  cut  squarely 
into  the  tooth  but  little  more  than  through  the  enamel,  and  with 
square  angles  toward  the  incisal.  They  do  not  appear  in  the 
lower  jaw,  but  appear  in  every  tooth  eroded  in  the  upper  jaw. 
This  ease  was  bilateral,  being  much  alike  on  the  two  sides. 

Wedge-shaped  aeeas.  These  are  the  "keilformige  defecte" 
of  German  writers.  This  form  usually  has  its  place  of  beginning 
near  the  free  margin  of  the  gum,  and  if  seen  at  its  beginning 
looks  like  a  little  groove  cut  across  the  crown  of  the  tooth  from 
mesial  to  distal.  These  gradually  deepen,  and  soon  the  case 
looks  as  if  a  wedge-shaped  piece  had  been  cut  out  of  the  labial 
surface  of  the  tooth,  presenting  a  flat  side  reaching  toward  the 
gingival  and  a  square  shoulder  toward  the  occlusal,  as  if  filed 
away  with  a  square  file.  In  many  of  the  cases  the  cut  is  as  square 
and  the  angles  as  sharp  as  they  could  be  made  with  such  an 
instrument.  In  others  there  is  more  inclination  to  rounding 
of  the  angle  in  the  deeper  part  of  the  cut. 


44  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE    TEETH. 

I  had  supposed  that  this  form  of  erosion  was  the  prevailing 
form  in  Germany,  for  in  taking  up  the  German  writers  I  have 
found  that  generally  they  have  illustrated  this  form  only,  and 
generally  speak  of  erosion  as  the  "keilformige  defecte"  (wedge- 
shaped  defects).  Upon  inquiry,  however,  among  German  den- 
tists, I  find  that  other  forms  are  also  found,  but  they  think  this 
one  the  most  common.  I  have  seen  a  number  of  cases  of  this 
form  in  which  the  teeth  were  cut  through  so  deeply  that  they 
finally  broke  away,  cutting  through  the  calcified  pulp  without 
any  distinction  whatever  from  other  parts  of  the  dentin.  These 
wedge-shaped  areas  occur  both  in  the  upper  and  lower  jaws, 
less  frequently  in  the  incisors  in  the  upper  jaw,  but  more  fre- 
quently in  the  bicuspids  and  molars.  It  is  not  very  uncommon 
to  see  this  form  in  the  bicuspids  and  molars,  and  some  irregular 
forms  or  dish-shaped  areas  in  the  incisors  and  cuspids. 

In  Figure  51  is  shown  what  appears  to  be  a  modification  of 
the  wedge-shaped  areas  of  erosion,  occurring  in  two  bicuspids. 
In  the  deeper  parts  the  cuts  are  well  rounded  from  the  occlusal 
toward  the  gingival  margins,  but  are  flat  mesio-distally.  The 
form  is  that  of  a  segment  of  a  cylinder.  We  see  this  form  most 
in  bicuspids  and  molars,  but  it  may  occur  in  the  incisors  as  well. 
In  the  incisors,  however,  it  is  not  apt  to  cut  very  deeply,  so  far 
as  present  observation  shows.  It  is  more  likely  to  thin  out  and 
spread  broadly  over  the  labial  surface  of  the  tooth,  producing 
a  flat  labial  surface. 

In  Figure  52  is  presented  a  specimen  of  this,  occurring  in 
the  incisors  of  a  young  lady  about  nineteen  years  old.  Three 
casts  of  this  have  been  made  about  one  year  apart,  watching  its 
progress.  The  picture  presented  here  is  from  the  first  cast 
taken,  and  the  erosion  at  that  time  had  been  noticed  only  about 
one  year.  It  has  not  gone  deeper  since,  but  has  spread  consid- 
erably more  toward  the  incisal.  At  the  last  observation  it  seemed 
to  have  become  stationary,  all  sensitiveness  had  disappeared 
and  tlie  teeth  were  perfectly  comfortable.  The  cutting  is  so 
shallow  that  the  teeth  are  not  deformed  so  much  as  to  be  noticed 
in  ordinary  conversation.  It  required  careful  adjustment  of 
light  to  get  sufficient  light  and  shade  to  make  a  good  picture. 

Flattened  areas.  The  tendency  seems  evidently  toward  the 
flat  form,  which  is  prominently  presented  in  Figure  53.  This 
case  was  from  a  man  about  sixty  years  old,  a  laborer.  He  had 
apparently  taken  no  care  of  his  teeth,  and  claims  that  he  never 
used  a  brush  in  his  life.  In  this  it  will  be  noted  in  the  cuspid 
on  the  left  of  the  picture,  that  the  cutting  has  begun  and  gone 


Fin.  r.O.  Th«*  wc.l^'o-shapi'tl  an^as  of  nosioii,  of  llic  "  keiUnnnitfo  drfrcte  "  of  German  authovs. 
An  excellent  example  of  that  form  of  erosion  in  which  a  wedge-shaped  piece  is  removed.  In  this  case 
the  thin  edge  of  the  wedge  is  toward  the  gingival  margin.  Only  the  lower  teeth  are  eroded.  Patient, 
a  woman  about  forty  years  of  age. 

FiQ.  51.  A  modification  of  the  wedge-shaped  areas  of  erosion  in  which  the  bottom  of  the  cut  ia 
well  rounded  instead  of  a  sharp  angle.  This  form  is  frequent  in  the  bicuspids  and  first  molars. 
Patient,  a  man  thirty-five  years  of  age.     No  other  erosion  had  occurred  in  the  mouth. 

61) 


Fio.   b2. 


ri|«ffl« 


KlQ.   53. 


Fig  52.  An  early  stage  of  what  promises  to  be  the  Bat  form,  which  in  its  earliest  beginning  is 
often  much  like  the  w'Ldge.shape.  The%xtension  is  toward  the  iy^^^fw  *'' Patient""  a^^rininet  en 
cupping  from  mesial  to  distal.      In  these,   the  cuttmg  is  generally  shallow.     Patient,   a  girl  nineteen 

years  of  age.  j        *  ■ 

Fig  63.  The  fiat  form  in  an  advanced  stage,  but  with  a  cuspid  but  little  advanced,  and  a  tri- 
angular patch  of  enamel  still  left  on  one  lateral  and  one  central  incisor  of  the  "PPer  .!-™-  A  man 
about  siAy  years  of  age ;    a  laborer,  who  avers  that  he  never  owned  or  used  a  tooth  brush. 


V 


FiQ.    54. 


Fjfl.   55. 


Fig.  54.  A  flat  form  which  ran  a  very  rapid  course,  complicated  with  erosion  of  the  proximal  sur- 
faces. The  small  fig-ure  on  the  right  is  a  labio-lingual  section,  intended  to  give  more  definite  informa- 
tion as  to  the  loss  of  substance.  The  incisors  were  destroyed  within  five  years  after  the  erosion  was 
first  seen.     From  a  man  of  wealth  about  sixty  years  of  age. 

Fig.  55.  .\  flat  fonn  complicated  by  erosion  of  the  proximal  surfaces,  which  are  also  flat.  No 
erosion  of  the  lower  teeth  or  any  of  the  bicuspids  or  molars.  The  upper  incisors  had  overlapped  the 
lower  nomially  before  the  erosion  shortened  the  teeth.  This  case  presented  extreme  sensitiveness  of  the 
eroded  areas.     \  man  twenty-eight  years  of  age,  a  bookkeeper. 


FlQ.   57 


Fig.  56.  A  type  of  the  irre^lar  form.  Some  of  these  present  sin^lar  extravagances.  Man, 
about  forty  years  of  age. 

FiQ.  57.  The  pattern  form,  or  figure  cutting.  In  this  particular  case,  in  the  right  central  incisor 
one  horizontal  and  one  perpendicular  groove  are  cut,  which  are  joined,  forming  a  right  angle,  and 
there  is  also  a  groove  in  the  labial  portion  of  the  incisal  edge  joining  at  a  right  angle  with  the  per- 
pendicular groove.  A  similar  figure  is  being  outlined  upon  the  opposite  central  incisor.  Patient,  a 
girl,  nineteen  years  of  age. 


EEOSION   OF   THE   TEETH.  45 

but  a  little  way.  In  the  lateral  incisor  nearly  all  of  the  labial 
surface  has  been  removed,  but  a  triangular  patch  is  left  at  the 
incisal  edge,  in  which  the  enamel  seems  not  to  have  been  injured 
in  the  least.  In  the  central  incisor  on  that  side,  another  triangu- 
lar patch  of  enamel  is  left,  next  to  the  proximating  central,  in 
the  same  condition.  On  these  triangular  areas  the  surface  of 
the  enamel  remains  perfect.  In  the  opposite  lateral  incisor  and 
cuspid  there  is  some  cupping  of  the  surface,  but  they  are  nearly 
flat.  The  incisors  are  cut  pretty  deeply  at  the  gingival  portion 
of  the  crown.  The  gums  are  in  very  good  condition.  It  will  be 
noticed  that  the  lower  teeth  are  irregular  and  that  the  cuspid 
on  the  right  of  the  picture  occludes  evenly  with  the  upper  incis- 
ors. This  cuspid  presents  a  perfectly  flattened  labial  surface 
throughout  its  extent  from  mesial  to  distal,  but  from  incisal  to 
gingival  it  is  a  little  concave.  The  lateral  incisor  next  to  it 
is  cut  through  its  length  as  though  it  had  been  cut  in  a  planing 
mill,  it  is  so  level  and  perfect,  with  almost  perfectly  squared 
edges  on  either  side  of  the  cut,  the  progress  seeming  to  be  to  the 
mesial  and  to  the  distal  of  the  central  cut.  These  characteristics 
are  not  so  often  seen  as  some  of  those  described  earlier,  and  this 
case  presents  very  remarkable  peculiarities  in  the  triangular 
patches  of  enamel  left  at  the  time  the  cast  was  made. 

Figure  54  presents  another  case  which,  while  it  looks  similar, 
is  really  quite  different.  This  occurred  in  a  man  about  sixty-five 
years  old,  and  had  been  seen  and  watched  for  a  number  of  years 
by  one  of  our  most  intelligent  practitioners.  The  course  of  the 
erosion  was  very  rapid,  occupying  but  between  three  and  four 
years.  In  this  the  erosion  began  near  the  center  of  the  labial 
surfaces  and  spread  more  rapidly  toward  the  incisal  than  toward 
the  gingival,  and  the  incisal  edge  was  soon  invaded.  The  proxi- 
mal surfaces  also  began  to  lose  material  and  the  centrals  spread 
apart.  In  this  case  there  was  not  the  perfect  smoothness  of 
surface  usually  seen  in  cases  of  erosion,  and  it  reminded  me 
very  much  of  a  case  described  by  Dr.  Kirk,  in  which  he  thought 
there  was  an  inclination  to  softening  upon  the  surface,  although 
there  was  no  actual  softening  discernible.  The  teeth  in  this 
case,  Figure  54,  gave  a  great  deal  of  trouble  from  sensitiveness, 
but  artificial  crowns  placed  upon  them  are  doing  very  well. 

The  next  case.  Figure  55,  is  somewhat  similar  in  its  nature. 
This  case  was  brought  in  to  me  for  advice  by  the  dentist  in  charge, 
and  when  I  first  looked  at  the  mouth  at  a  distance  of  a  few  feet, 
my  impression  was  that  the  upper  incisors  were  retained  decid- 
uous teeth,  but  closer  inspection  dispelled  this  idea  at  once.    The 


46  PATHOLOGY   OF   THE  HABD   TISSUES   OF   THE   TEETH. 

gentleman  was  about  twenty-eight  years  old,  and  the  normal 
wear  where  the  lower  teeth  had  occluded  against  the  lingual 
surfaces  of  the  upper  incisors  was  unmistakable,  showing  that 
it  had  not  been  very  long  in  progress.  The  teeth  were  so  sensi- 
tive that  the  patient  was  greatly  annoyed,  and  was  seeking  relief. 
The  teeth  were  cut  in  such  a  way  as  to  cup  them  out  slightly  upon 
the  labial  surfaces.  The  proximal  surfaces  were  wasting  per- 
haps as  much  as  the  labial  surfaces,  but  were  cut  pretty  squarely 
almost  as  though  they  had  been  filed.  The  teeth  showed  no  traces 
of  scratches  of  any  kind,  but  they  were  not  as  smooth  and  glossy 
as  most  cases  of  erosion;  they  were  more  like  the  one  last 
described.  In  this  case  I  advised  that  porcelain  crowns  be  placed 
on  the  teeth  after  devitalization. 

Irregulab  AREAS.  In  Figure  56  is  presented  another  class 
of  case  entirely,  which  will  be  described  under  the  head  of  irreg- 
ular areas.  In  this  case  there  are  grooves  passing  across  the 
teeth  from  mesial  to  distal,  not  always  at  the  same  angle  nor  of 
the  same  depth,  some  appearing  upon  the  mesial  most,  and 
others  appearing  upon  the  distal  most,  and  so  on.  Occasionally 
I  see  this  with  the  groove  reaching  not  more  than  half  across 
the  labial  surface  of  the  tooth,  but  cutting  very  deeply ;  in  fact, 
they  may  present  almost  any  form,  but  generally  in  grooves  from 
mesial  to  distal. 

In  one  case  that  came  under  my  observation  a  single  groove 
was  cut  across  the  teeth  at  about  the  middle  of  the  length  of  the 
crown,  less  than  two  millimeters  wide,  and  cut  squarely  in,  fully 
one-half  through  the  tooth,  affecting  the  two  centrals  and  one 
lateral.  This  case  occurred  in  my  own  practice  a  number  of 
years  ago  when  I  was  trying  to  prevent  the  spreading  of  erosion 
by  filling,  and  in  this  case  it  was  cut  so  squarely  that  I  fUled  with 
gold  the  cavities  formed  in  the  centrals  without  any  excavation 
whatever.  I  had  the  satisfaction  of  seeing  these  fillings  remain 
perfect  until  the  time  of  the  gentleman's  death,  some  ten  years 
later.  No  renewal  whatever  of  the  erosion  occurred.  In  a  large 
collection  of  casts,  a  good  many  of  these  irregular  cuts  may  be 
found. 

Figured  areas.  In  Figure  57  is  presented  an  illustration  of 
what  may  be  designated  as  figure  cutting  in  erosion,  that  is, 
cases  in  which  the  erosion  takes  a  form  of  some  particular  com- 
plex type.  In  tliis,  in  the  central  incisor  on  the  left  of  the  figure, 
a  rounded  groove  is  cut  across  the  labial  face  of  the  tooth  near 
the  junction  of  the  middle  and  gingival  thirds.  From  that  a 
groove  is  cut  along  the  mesial  border  straight  to  the  incisal  edge, 


"*'«*l*^^ 


Fia. 


FifiS.  58.  59,  60.  Pattom  form  more  advanced.  The  cut  acrosK  the  root  of  the  tooth  was  made 
with  tho  file  for  the  oxainiiiation  of  the  condition  of  Iho  pulp  clianibor  as  to  culoiflcation.  Notice  that 
a  second  groove  was  starting  on  the  distal  portion  of  the  rn>\vn.  Kiciirc  59  shows  the  depth  of  tho 
perpendicular  groove  at  the  incisal  edge,  and  Figure  GO  thn  depth  nf  (he  horizontal  groove. 


EBOSION   OP   THE   TEETH.  47 

and  then  the  incisal  edge  is  squarely  grooved  across  the  labial 
portion  of  its  edge.  The  cutting  upon  the  fellow  central  incisor 
has  started  in  the  same  way  and  will  follow  the  same  course.  A 
case  seen  a  number  of  years  ago  with  Dr.  Gushing  was  almost 
precisely  the  same  as  this  in  figure,  except  that  the  groove  reach- 
ing the  incisal  surface,  grooved  the  incisal  surface  and  then 
extended  to  the  lingual  along  the  mesial  margin  of  the  lingual 
surface.  The  teeth  were  long  cusp  teeth.  They  were  practically 
unworn  and  there  was  no  reason  whatever  to  attribute  the  groov- 
ing on  the  lingual  surface  to  abrasion. 

Figures  58,  59  and  60  illustrate  another  case  of  figure  cut- 
ting that  is  much  more  extensive.  In  this  case  there  was  no 
grooving  of  the  incisal  edge,  or  along  the  incisal  edge,  only  a 
slight  broadening  of  the  groove  on  the  mesial  side,  and  it  will 
be  noted  that  a  similar  groove  is  being  cut  upon  the  distal  portion 
of  the  labial  surface,  while  there  is  a  curious  half  dish-shaped 
form  on  the  distal  end  of  the  groove  running  mesio-distally.  In 
this  cutting,  the  angles  with  the  surface  of  the  tooth  are  very 
sharp,  but  the  bottoms  of  the  grooves  are  well  rounded.  The 
depth  of  the  cut  from  the  transverse  groove  to  the  incisal  is 
shown  in  Figure  59,  while  the  depth  of  the  cut  across  the  labial 
surface  is  shown  in  Figure  60. 

It  was  clearly  apparent  in  examination  of  the  tooth,  that 
the  groove  running  mesio-distally  had  cut  through  the  calcified 
pulp.  The  incisal  edge  of  the  tooth  had  been  much  worn  by 
ordinary  abrasion.  The  V-shaped  cut  in  the  root  of  the  tooth 
was  made  with  a  file  for  the  examination  of  the  pulp  canal. 

In  all  my  examinations  of  erosion  I  have  never  seen  a  metal- 
lic filling  that  seemed  to  have  been  cut  away  by  erosion.  Years 
ago  I  made  much  trial  of  gold  fillings  with  a  view  of  arresting 
erosion,  and  generally  found  the  erosion  progressing  beside  the 
filling  as  though  no  filling  had  been  placed.  The  margins  of  the 
fillings  stood  up  sharp  and  definite,  showing  no  rounding.  Dr. 
W.  D.  Miller,  in  his  recent  articles  on  erosion,  claimed  to  have 
seen  fillings  of  various  sorts  cut  away  by  this  process.  Recently 
I  have  met  with  a  case  which  is  presented  in  Figure  61,  in  which 
a  gold  crown,  which  had  been  placed  over  the  first  bicuspid, 
seems  to  have  been  cut  through.  The  patient  is  a  dentist,  and  he 
tells  me  that  this  is  the  third  gold  crown  that  has  been  cut 
through  at  the  same  point.  It  was  placed  over  the  tooth  because 
it  had  become  quite  deeply  eroded  and  was  extremely  sensitive. 
The  second  bicuspid  below  also  is  a  gold  crown,  placed  for  a 
similar  reason.     It  has  shown  no  signs  of  injury.     It  wiU  be 


48  PATHOLOGY   OF    THE    HARD   TISSUES   OF    THE   TEETH. 

noted  that  erosion  is  in  progress  in  other  teeth  in  the  neigh- 
borhood. 

In  Figure  62  is  presented  an  illustration  of  a  ease  of  erosion 
of  proximal  surfaces  observed  a  number  of  years  ago.  The  pic- 
ture is  reproduced  from  pencil  sketches  made  during  the  progress 
of  the  case.  I  had  the  privilege  of  observing  the  progress  of  this 
over  a  period  of  about  seven  years,  nothing  being  done  or 
attempted  in  the  way  of  treatment.  The  picture  represents  the 
case  as  I  first  observed  it.  It  appeared  as  if  holes  had  been 
bored  between  the  teeth,  cutting  about  equally  from  either  tooth. 
These  grew  larger  and  larger  and  the  interproximal  gum  tissue 
receded  slightly  until  the  teeth  were  cut  away  so  much  that  they 
broke,  leaving  the  roots  in  position.  During  all  of  this  time,  the 
margins  of  the  cut  at  their  junction  with  the  enamel  surface 
were  sharp,  presenting  no  observable  rounding.  I  have  observed 
this  in  the  molars  and  bicuspids  in  several  cases,  and  usually 
the  teeth  have  been  extremely  sensitive.  One  gentleman  had 
all  of  his  molars  removed  from  the  upper  jaw  bcause  of  the  pain 
they  gave  him  in  chewing  food  and  in  any  effort  to  clean  his  teeth. 

The  selection  of  cases  for  illustration  has  been  confined  to 
a  few  which  seem  to  represent  the  more  typical  varieties  of 
form.  Variations  from  these,  however,  are  constantly  coming 
up,  almost  every  new  case  presenting  characters  peculiar  to 
itself.  Many  of  them,  even  when  the  teeth  are  badly  cut  and 
deformed,  are  so  clean  and  white  that  the  deformity  is  scarcely 
noticeable  a  few  feet  away.  But  occasionally  we  see  cases  that 
give  a  very  bad  appearance.  A  larger  list  of  illustrations  would 
present  variations  without  giving  essentially  new  forms.  For 
instance,  the  case  from  which  the  irregular  cutting  of  the  incisors 
was  taken  for  Figure  56  had  wedge-shaped  areas  of  erosion  at 
the  gingival  of  the  bicuspids  and  molars  in  which  the  point  of 
the  wedge,  and  of  course  the  flat  side  of  the  cut,  sloped  toward 
the  occlusal  instead  of  toward  the  gingival,  as  shown  in  Figure 
50,  which  is  the  more  common,  and  therefore  the  more  typical  of 
the  wedge-shaped  areas.  Similar  changes  from  anything  that 
may  be  regarded  as  typical  are  continually  occurring.  These 
are  curious,  but  further  illustration  would  give  no  broader  view 
of  the  general  subject. 

Whether  or  not  these  forms  of  erosion  have  any  significance 
in  connection  with  the  causation,  can  at  present  be  only  a  matter 
of  speculation.  In  studying  them  it  would  seem  that  if  some 
eases  of  erosion  are  caused  by  the  brush  carrying  abrasive 
powders,  certain  of  the  forms  may  be  due  to  that,  while  certain 


Fio.   G2. 


Fig.  61.  Dish  shapes.  The  lower  bicuspids  and  first  molar  are  gold  shell  crowns,  which  were 
phiced  lecause  of  the  extreme  sensitiveness  of  the  eroded  areas.  The  crown  on  the  first  bicuspid  is  the 
third  shell  crown  which  has  been  worn  through  by  the  erosion.  The  white  cement  may  be  seen  through 
tlie  hole  in  the  crown.     Man,  forty  3'ears  of  nge ;    a  dentist. 

Fig.  ij'2.  Proximal  surface  erosion.  A  case  of  a  young  man,  about  nineteen  jcars  of  age.  When 
first  observed  the  teeth  were  in  tire  condition  presented  in  this  illustration,  showing  round  holes  through 
between  the  teeth.     These  enlarged  slowly,  and  the  teeth  broke  away  about  seven  years  later. 


EKOSION    OF    THE   TEETH.  49 

other  of  the  forms  would  seem  to  be  impossible  of  production  in 
that  way.  For  the  present  there  does  not  seem  to  be  sufficient 
basis  for  any  considerable  discussion  of  this  point. 

Etiology  of  Erosion. 

The  cause  of  erosion  is  involved  in  the  utmost  obscurity. 
Most  observers  seem  to  have  drawn  their  opinions  of  its  caus- 
ation from  the  observation  of  the  circumstances  attending  a 
comparatively  small  number  of  cases  coming  under  their  per- 
sonal observation.  As  the  cases  differ  very  materially  in  form 
of  affected  areas  and  surroundings,  these  views  differ  with 
the  groups  of  cases  observed.  These  opinions  may  be  found  in 
the  literature  reaching  back  some  two  hundred  years.  I  may, 
perhaps,  give  a  better  and  more  condensed  idea  of  this  by  group- 
ing these  opinions  into  classes,  than  by  extensive  quotations.  I 
will  follow  in  some  degree  the  order  in  which  they  have  been 
prominent  in  the  literature.    They  may  be  thus  summarized : 

(1.)  Erosion  is  a  result  of  faults  in  the  formation  of  the 
tissues  during  the  growth  of  the  teeth;  conditions  in  after  life 
have  little  or  nothing  to  do  with  it. 

(2.)  Erosion  is  caused  by  friction,  most  generally  of  the 
tooth  brush  carrying  some  abrasive  tooth  powder. 

(3.)  Erosion  is  the  result  of  the  action  of  an  acid  in  some 
way,  as  yet  unknown  to  us. 

(4.)  Erosion  is  the  direct  result  of  the  action  of  a  secretion 
of  certain  diseased  glands  in  the  mucous  membranes  that  lie 
directly  upon  the  areas  being  eroded.  This  secretion  is  gen- 
erally claimed  to  be  acid  in  its  reaction. 

(5.)  Erosion  is  a  process  of  absorption  similar  to  that  of 
the  removal  of  the  roots  of  the  deciduous  teeth  or  the  occasional 
absorption  of  the  roots  of  the  permanent  teeth.  The  absorbing 
tissue  is  the  diseased  portion  of  mucous  membrane  found  Ijdng 
in  the  eroded  areas. 

(6.)  Erosion  is  in  some  way  the  action  of  an  acid,  the  devel- 
opment of  which  is  associated  with  the  gouty  diathesis. 

(7.)  Erosion  is  effected  by  alkaline  fluids  acting  upon  the 
basic  substance  and  setting  the  calcium  salts  free,  which  waste 
away  with  a  polished  surface. 

(8.)  While  dental  caries  is  the  result  of  the  action  of  an 
acid  developed  by  microorganisms,  erosion  is  effected  by  the 
enzyme  of  the  same  or  similar  microorganisms. 

In  discussing  briefly  the  principal  points  in  these  views,  we 
will  find  some  overlapping  more  or  less  with  each  other,  or 

1 


50  PATHOLOGY   OF   THE    HABD    TISSUES    OF    THE    TEETH. 

separated  only  by  the  introduction  of  certain  factors  supposed 
important  by  one  party,  but  not  considered  so  by  another. 

The  FmsT  supposition  mentioned  seems  to  have  been  the 
older  view.  It  was  clearly  expressed  by  John  Hunter  in  1778, 
by  Fox  in  1806,  by  Bell  in  1825,  and  by  a  number  of  others  fol- 
lowing these,  and  finally  by  Garretson  as  late  as  1890. 

Himter  supposes  that  erosion  is  due  to  some  certain  imper- 
fection in  the  formation  of  the  tissues  of  the  tooth,  because  of 
which  the  substance  gradually  wastes  away,  continually  leaving 
a  smooth  surface.  His  supposition  seems  to  have  been  that 
conditions  in  after  life  had  nothing  especially  to  do  in  the  matter. 

Fox  and  Bell  do  not  differ  materially  from  this  view,  but 
Bell  adds  the  supposition  that  in  the  case  of  the  dish-shaped 
areas  of  erosion,  the  tissues  of  the  tooth  have  been  deposited 
in  whorls  or  such  forms  as  favored  this  kind  of  wasting.  To-day 
such  views  seem  very  strange;  but  we  should  remember  that 
when  these  men  wrote  nothing  was  known  of  the  histology  of 
the  teeth,  and  their  view  did  no  violence  to  facts  known  in  their 
time.  We  now  know  that  such  faults  in  the  formation  of  the 
tissues  do  not  occur  as  the  basis  of  these  cases. 

The  second  supposition,  i.  e.,  that  erosion  is  caused  by  fric- 
tion, and  generally  by  the  tooth  brush  loaded  with  abrasive 
powders,  was  held  by  John  Tomes  and  many  others  in  England, 
America  and  Germany,  and  is  still  held  by  many  observers. 
According  to  this  view  erosion  is  no  disease  at  all,  but  is  purely 
a  mechanical  injury.  Conditions  present  in  quite  a  number  of 
the  cases  seen,  if  grouped  together  and  considered  alone,  would 
give  strong  support  to  this  view.  These  cases  nearly  all  belong 
to  the  more  indefinite  shapes  of  the  wedge-like  forms,  and  the 
cases  which  occur  in  the  cementum  after,  or  with,  recession  of 
the  gum.  A  number  of  persons  who  hold  this  view  describe  and 
illustrate  these  forms  only.  This  has  led  me  to  suspect  that  in 
some  regions,  particular  forms  are  more  frequently  met  than 
others.  It  seems  certain  that  in  the  central  part  of  the  United 
States  one  would  not  observe  many  cases  of  the  wedge-shaped 
areas  without  finding  varieties  of  form  that  would  be  very  difiicult 
to  explain  as  resulting  from  abrasion  by  the  tooth  brush.  When 
Charles  Tomes  edited  another  edition  of  his  father's  work,  he 
had  seen  cases  that  he  believed  could  not  have  been  made  with 
the  tooth  brush,  and  he  rewrote  the  chapter  entire.  Dr.  C.  R.  E. 
Koch  (Dental  Cosmos,  Volume  15, 1873,  page  463)  tried  by  every 
device  he  could  think  of  to  produce  the  conditions  seen  in  erosion 
by  the  use  of  brushes  and  brush  wheels,  aided  by  acids  in  some 


KBOSION    OF    THE   TEETH.  51 

cases  and  by  alkalies  in  others.  His  conclusion  was  that  it  could 
not  be  done  in  any  of  these  ways.  He  did  not  have  the  modern 
electric  motor  to  run  his  brushes,  however. 

Dr.  W.  D.  Miller,  of  Berlin,  Germany,  recently  published 
(Dental  Cosmos  of  January  and  February,  1907)  the  results  of 
two  years'  work  on  the  etiology  of  erosion.  He  announced  his 
belief  that  it  is  caused  by  weak  acids  or  gritty  tooth  powders,  or 
by  both,  assisted  by  the  tooth  brush.  He  seemed  to  be  convinced 
that  the  tooth  brush  is  the  main  factor,  and  that  what  we  have 
designated  as  erosion  is  nothing  more  nor  less  than  abrasiom 
brought  about  by  these  agencies. 

During  several  weeks  that  the  author  was  in  Berlin  during 
the  summer  of  1906,  he  was  frequently  in  Dr.  Miller's  laboratory 
while  he  was  engaged  in  these  studies.  Through  his  kindness 
much  was  seen  of  his  plans  of  work  in  the  effort  to  produce 
erosion  by  artificial  means.  Having  placed  a  number  of  teeth 
in  wax,  gutta  percha,  or  similar  substance,  somewhat  in  the  form 
they  would  be  in  the  mouth,  he  saturated  a  cloth  with  a  weak 
acid  solution  (different  solutions  being  used  in  various  experi- 
ments) and  laid  it  lightly  over  the  teeth  so  that  it  would  touch 
only  on  the  most  prominent  part  of  their  crowns.  After  this 
had  remained  in  a  moist  chamber,  intended  to  prevent  too  much 
evaporation,  for  a  predetermined  length  of  time,  the  cloth  was 
removed  and  the  preparation  placed  on  a  machine  run  by  an 
electric  motor,  and  the  teeth  were  vigorously  brushed  for  a 
given  number  of  minutes  or  hours,  as  determined  for  the  par- 
ticular case.  The  cloth  was  then  resaturated  with  the  acid  solu- 
tion, placed  again  upon  the  teeth,  and  the  preparation  returned 
to  the  moist  chamber  for  the  predetermined  number  of  hours 
for  that  experiment.  This  was  kept  up  day  after  day  for  weeks 
or  for  months,  the  experiments  being  much  varied  as  to  acid 
solutions,  time,  and  brushing;  also,  certain  experiments  were 
being  carried  on  without  the  acid  solutions,  and  others  by  the 
use  of  tooth  powders  in  use  by  the  people.  In  some  of  the  experi- 
ments the  brushing  was  done  by  hand,  as  by  this  method  more 
variety  of  motion  could  be  used. 

In  these  ways  he  had  certainly  produced  results  that  looked 
very  much  like  many  cases  of  erosion  as  seen  in  the  mouth, 
especially  those  of  the  partially  dish-shaped,  the  wedge-shaped, 
and  the  flattened  varieties.  I  saw  none  of  his  artificial  produc- 
tion, however,  that  had  the  sharp,  clean-cut  margins  so  often 
present  in  the  real  thing  as  it  occurs  in  the  mouth.  Yet  I  feel 
certain  that  if  these  specimens  had  been  presented  to  me  as 


52  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

erosions  that  had  occurred  in  the  mouth  in  the  ordinary  way, 
I  should  not  have  questioned  their  genuineness.  Certainly  Dr. 
Miller  has  demonstrated  the  possibility  and  the  probability  that 
teeth  are  often  injured  by  vigorous  brushing  with  gritty  powders, 
persisted  in  several  times  per  day  for  many  years  together.  I 
am  not  j^et  convinced,  however,  that  all  erosions  are  produced 
in  this  way,  even  admitting  that  they  may  be  assisted  in  part  by 
an  acid  that  may  be  present  in  the  fluids  of  the  mouth. 

One  thing  particularly  Dr.  Miller  seems  to  have  ignored, 
and  that  is  the  extreme  sensitiveness  that  is  so  often  present  in 
cases  of  erosion.  I  know,  however,  that  Dr.  Miller  had  not  fin- 
ished his  investigation  of  the  subject  at  the  time  of  his  death, 
and  that  the  peculiar  sensitiveness  occurring  in  erosion  would 
have  been  considered  by  him  later  if  he  had  had  the  opportunity. 
This  I  have  regarded  as  peculiar  to  erosion,  admitting,  however, 
that  cases  occur  in  which  there  is  no  history  of  this  symptom. 
It  is  my  belief,  based  on  the  examination  of  many  cases,  that 
frequently  sensitiveness  is  soon  annulled  by  the  rapid  calcifi- 
cation of  the  pulps  of  the  teeth.  This  has  the  effect  of  cutting 
off  the  connection  of  the  dentinal  fibrils  of  the  crown  of  the  tooth 
with  the  remaining  pulp  tissue.  Then  sensitiveness  is  ended. 
Therefore,  many  of  the  bad  cases  of  erosion  have  not  been  sensi- 
tive for  several  years.  This  calcification  has  been  a  result  of 
the  condition  of  irritation  communicated  through  the  dentinal 
fibrils. 

During  the  time  of  this  irritable  condition  there  is  generally 
a  history  of  the  cessation  of  brushing,  for  the  reason  that  the 
friction  of  the  brush  can  not  be  borne.  In  the  case  illustrated 
in  Figure  55,  the  young  man  said  he  had  used  a  brush  before 
his  teeth  became  so  sensitive,  but  most  of  the  loss  of  substance 
had  occurred  afterward.  This  is  but  a  repetition  of  the  history 
I  have  had  from  many  persons. 

The  THIRD  SUPPOSITION  —  that  it  is  the  action  of  an  acid  — 
has  been  held  by  many  persons,  and  in  one  form  or  other  prob- 
ably has  more  adherents  to-day  than  any  other.  How  it  is  that 
an  acid  can  so  act  to  cut  away  the  substance  of  the  tooth,  leaving 
a  hard,  polished  surface  which  is  a  constant  characteristic  of 
erosion,  while  in  all  laboratory  experiment  and  in  caries  as  it 
occurs  in  the  mouth  the  effect  is  a  gradual  softening  by  the 
solution  of  the  calcium  salts,  is  left  unexplained,  unless  Dr. 
^Miller's  work  noted  above  may  be  so  regarded.  As  yet  no  acid 
has  been  found  tliat  will  remove  the  whole  of  the  tissue,  calcium 
salts  and  basic  substance,  without  previous  softening. 


BEOSION   OF   THE   TEETH.  53 

I  have  made  some  experiments  on  a  different  plan  (reported 
with  illustrations  in  the  "vVmerican  System  of  Dentistry,"  Vol- 
ume I,  page  1003).  Having  noticed  in  some  experimental  work 
on  the  metals  that  the  action  of  very  dilute  acids  was  different 
in  the  still  condition  as  compared  with  the  action  in  currents,  I 
tried  this  upon  teeth.  Here  I  also  found  a  difference.  In  a 
rapid  current  of  a  solution  of  one  part  of  hydrochloric  acid  to 
four  hundred  parts  of  water,  maintained  for  five  days  contin- 
uously, teeth  were  cut  away  in  forms  quite  similar  to  erosion, 
the  cut  surfaces  remaining  hard  and  smooth  while  other  portions 
of  the  teeth  were  not  softened.  I  found  the  loss  of  substance  to 
occur  only  where  the  current  broke  around  the  teeth  in  a  certain 
way.  While  this  experiment  is  impossible  of  comparison  with 
anything  that  can  occur  in  the  human  mouth,  it  demonstrates 
the  possibility  that  the  action  of  acid  solutions  may  be  modified 
in  some  degree  by  conditions  under  which  they  are  placed.  Thus 
far,  however,  no  modification  has  been  discovered  that  will  in 
any  degree  account  for  effects  like  those  seen  in  erosion  under 
conditions  that  seem  possible  in  the  human  mouth. 

The  fourth  supposition  —  that  erosion  is  caused  by  the 
secretion  of  certain  glands  in  the  mucous  membrane  of  the  lips 
and  cheeks,  that  these  glands  become  inflamed,  or  hj'pertrophied, 
from  some  unexplained  cause,  and  emit  an  abnormal  secretion 
which  acts  upon  the  teeth  in  this  peculiar  manner.  It  is  certainly 
true  in  many  of  the  dish-shaped  eroded  areas  in  incisors  par- 
ticularly, that  a  certain  part  of  the  mucous  membrane  is  found 
to  be  raised  in  a  form  that  fits  into  the  excavations  in  the  teeth. 
If  we  touch  these  with  blue  litmus,  it  is  instantly  reddened,  show- 
ing the  fluids  in  the  region  to  be  acid.  Several  have  remarked 
that  this  was  especially  true  when  the  test  is  made  early  in  the 
morning,  or  when  rising  from  bed. 

I  have  personally  examined  many  of  these  cases  and  have 
found  the  facts  as  stated.  I  have  also  found  in  these  cases  the 
prints  of  teeth  not  eroded  clearly  outlined  in  the  mucous  mem- 
branes, and  these  parts  of  the  membrane  showed  also  the  same 
acidity  when  tested  with  litmus.  After  a  careful  and  somewhat 
protracted  study  of  these  phenomena,  my  conclusion  is  that  the 
little  swellings  on  the  mucous  membranes  are  caused  by  the 
erosion,  rather  than  the  erosion  by  a  secretion  which  they  emit. 
In  a  considerable  number  of  persons  we  will  find  prints  of  the 
teeth  —  the  upper  incisors  particularly,  and  sometimes  the 
bicuspids  and  molars  also  —  in  the  lips  or  buccal  membranes, 
and  these  are  formed  in  the  same  manner. 


54  PATHOLOGY   OF   THE   HABD   TISSUES   OF   THE   TEETH. 

This  explanation  is  strongly  emphasized  by  the  fact  that 
erosions  occur  in  cases  in  which  the  mucous  membranes  never 
touch  the  teeth,  as  in  the  somewhat  rare  cases  of  erosion  of 
proximal  surfaces,  and  in  one  case  coming  under  my  observa- 
tion in  a  girl  sixteen  years  old,  in  which  the  bicuspids  were  deeply 
eroded  in  dish-shaped  forms,  where  the  tissues  of  the  cheek  had 
been  destroyed  before  the  teeth  came  through  the  gums,  so  that 
no  mucous  membrane  could  have  touched  them. 

The  FIFTH  SUPPOSITION  has  certain  jjoints  of  similarity  with 
the  fourth  in  that  the  same  raised  points  of  the  mucous  mem- 
brane are  described  as  fitting  into  the  eroded  areas.  But  instead 
of  the  erosion  being  caused  by  an  acid,  the  supposition  is  that 
this  tissue  acts  as  an  absorbing  organ,  and  that  the  result  is 
really  an  absorption  similar  to  that  by  which  the  roots  of  the 
teeth  are  cut  away.  Several  writers  speak  of  having  seen  the 
usual  lacuns  of  absorbed  areas  in  roots  of  teeth  and  in  areas 
of  bone  undergoing  absorption,  in  these  eroded  areas.  This 
supposition  necessarily  carries  with  it  the  idea  that  certain 
actively  functioning  cells  become  fixed  against  the  tooth  tissue 
and  keep  that  position  long  enough  or  steadily  enough  to  effect 
this  result.  The  same  objection  to  this  theory  applies  as  to  the 
previous  one,  namely,  that  cases  of  erosion  occur  in  positions 
in  which  no  mucous  membrane,  or  other  tissue,  is  in  contact  with 
the  areas  being  eroded.  Also  the  supposition  that  the  normal 
mucous  membrane,  or  the  mucous  membranes  in  any  probable 
pathological  condition,  would  throw  out  or  give  rise  to  absorptive 
cells  of  such  character  as  to  act  upon  the  teeth,  seems  imtenable 
without  further  data  than  we  yet  have. 

The  SIXTH  supposition  is  that  it  is  caused  by  an  acid  that 
is  developed  in  association  with  the  gouty  diathesis.  This  is  a 
more  recent  supposition.  Perhaps  the  most  notable  article  upon 
this  supposition  is  that  by  Dr.  Darby,  of  Philadelphia  (Dental 
Cosmos,  Volume  34, 1892,  page  629).  Dr.  E.  C.  Kirk,  of  the  same 
city,  has  expressed  somewhat  similar  views.  This  supposition 
has  rapidly  attained  pretty  wide  credence.  On  this  point  my 
own  observation,  so  far  as  it  goes,  would  be  negative.  Very 
little  gout  has  come  under  my  observation  (it  would  seem  that 
the  people  of  the  Mississippi  Valley  are  too  restless  a  set  of 
individuals  to  have  time  for  gout)  and  the  few  well-marked  cases 
that  I  have  had  opportunity  to  study  have  shown  no  erosion. 
It  seems,  however,  that  the  tendency  in  recent  years  to  attribute 
all  kinds  of  ills  not  otherwise  explainable,  to  the  gouty  or  rheu- 
matic dyscrasia,  has  been  carried  rather  too  far.    Yet  we  must 


EROSION    OF   THE   TEETH.  55 

now  expect  that  the  cause  of  erosion  will  eventually  be  found 
to  depend  upon  some  change  in  the  body  fluids  giving  oral  secre- 
tions favoring  these  results;  but  how,  by  what,  and  how  local- 
ized, are  the  questions.  For  the  present  it  seems  that  we  have 
no  certain  data  in  support  of  the  theory  connecting  it  with  the 
gouty  diathesis.  So  far  as  can  now  be  determined  from  reports 
from  other  localities,  it  seems  that  erosion  is  as  frequent  here 
where  gout  does  not  prevail  as  elsewhere. 

The  seventh  supposition  —  that  erosion  is  caused  by  alka- 
line fluids  acting  upon  the  basic  substance  of  the  tooth,  setting 
the  calcium  salts  free,  which  waste  away  leaving  a  polished  sur- 
face—  is  one  of  the  more  recent.  It  has  an  individuality  of 
its  own.  The  supposition  that  an  alkaline  condition  as  affecting 
litmus  is  maintained  in  these  localities  for  any  considerable 
part  of  the  time  is  certainly  contrary  to  my  personal  obser- 
vations, and  to  much  the  larger  number  of  recorded  observa- 
tions in  the  literature.  Further,  in  Dr.  Koch's  experimental 
work  mentioned  above,  he  found  that  he  could  not  dissolve  either 
enamel  or  dentin  in  alkalies  until  the  calcium  salts  had  been 
removed,  or  partially  removed  by  acids.  The  enamel  partic- 
ularly contains  so  little  organic  matter  that  it  would  seem  impos- 
sible—first, that  its  organic  matter  could  be  removed  in  that 
way,  and  second,  that  if  it  could  be  accomplished  it  would  not 
effect  the  disintegration  of  the  tissue.  The  dentin  has  a  much 
larger  proportion  of  organic  matter,  but  direct  experiment  seems 
to  show  that  it  has  sufficient  calcium  salts  to  protect  its  organic 
matter  from  solution  by  alkalies.  Therefore,  until  it  can  be 
shown  experimentally  that  in  some  possible  form  alkalies  will 
act  to  disintegrate  these  tissues,  this  supposition  must  be  set 
aside. 

The  eighth  supposition,  the  most  recent  of  all,  is  set  forth 
by  Preiswerk  in  his  " Zahnheilkunde "  ("Operative  Dentistry"), 
1903,  page  200.  It  is  the  supposition  that  erosion  is  caused  by 
the  same  or  similar  microorganisms  as  those  which  cause  caries, 
but  by  the  action  of  their  enzyme,  not  by  the  action  of  their  acid 
products.  It  is  well  known  that  a  number  of  the  microorgan- 
isms of  the  mouth  which  form  acids  in  the  presence  of  the  carbo- 
hydrates, such  as  sugar  or  starch,  will  grow  well  in  nutrient 
material  devoid  of  these  substances,  but  in  that  case  will  form 
no  acid  products.  Preiswerk  contends  that  the  human  saliva 
is  normally  alkaline,  and  that  it  is  a  mistake  to  suppose  that  the 
enzyme  of  these  microorganisms  is  necessarily  a  peptonoid  sub- 
stance, as  these  act  in  an  acid  medium.    He  claims  to  have  found 


56  PATHOLOGY   OF    THE   HARD    TISSUES    OF    THE   TEETH. 

evidence  that  in  alkaline  or  neutral  conditions  their  enzyme  is 
a  trypsin  similar  to  the  trypsin  of  the  pancreas  which  acts  in 
the  presence  of  an  alkaline  reaction.  Under  these  conditions 
this  enzyme  acts  upon  the  basic  substance  of  the  dental  tissues, 
dissolving  the  basic  substance,  setting  the  calcium  salts  free, 
vrhich  are  washed  away  during  the  chewing  of  food,  the  motions 
of  the  lips,  fluids  of  the  mouth,  and  in  the  artificial  cleaning  of 
the  teeth.  He  claims  to  have  in  some  degree  proven  this  propo- 
sition by  experiment  with  trypsin  derived  from  the  pancreas, 
which  he  found  to  act  upon  the  basic  substance  of  the  teeth. 

It  seems  quite  possible  that  trypsin  might  act  upon  bone 
in  this  manner,  possibly  upon  dentin,  but  that  it  should  so  act 
upon  enamel,  which  has  no  more  than  three  per  cent  of  basic 
substance,  seems  out  of  the  question.  Erosion  always  begins 
in  the  enamel,  except  in  those  cases  in  which  it  begins  in  the 
cementum  after  the  recession  of  the  gum  tissue,  and  practically 
always  cuts  the  enamel  as  smoothly  with  the  dentin  as  if  the  two 
were  one  and  the  same  tissue. 

In  the  absorption  of  the  roots  of  the  deciduous  teeth,  and 
not  very  rarely  of  the  permanent  teeth  as  well,  all  of  the  parts, 
basic  substance  and  calcium  salts,  are  cut  away  as  one  tissue.  In 
the  absorption  of  bone  by  the  normal  physiological  process,  the 
same  thing  occurs,  and  in  my  studies  of  these  processes  it  has 
often  been  observed  that  the  noncalcified  bone  corpuscles  suf- 
fered the  same  fate.  But  even  this  process  balks  at  enamel.  I 
have  often  met  with  enamel  in  position  to  be  acted  upon  by 
absorption,  but  this  had  failed.  We  often  see  almost  the  last 
trace  of  dentin  removed  from  the  crowns  of  deciduous  teeth 
by  physiological  absorption,  but  never  any  part  of  the  enamel. 
It  appears  at  the  present  time  that  these  facts  place  this  process 
out  of  the  question,  even  if  the  far  more  general  observation  — 
that  the  condition  is  acid  in  erosion  —  should  be  shown  to  be 
an  error. 

Finally,  I  can  not  at  present  find  any  theory  proposed,  nor 
have  I  any  to  propose,  that  has  not  features  that  seem  to  render 
it  impossible.  I  therefore  feel  compelled  to  leave  the  subject 
in  this  very  unsatisfactory  condition,  hoping  that  an  early  solu- 
tion of  the  difficulty  may  be  discovered.  It  seems  highly 
probable  that  this  will  be  found  connected  with  some  systemic 
dyscrasia,  but  if  so,  the  conditions  leading  to  its  strict  localiza- 
tion will  require  explanation. 


EEOSION    OF   THE   TEETH.  57 


Treatment  of  Erosion. 


At  present  no  treatment  with  the  view  of  cure  or  of  stopping 
the  progress  of  erosion,  is  known,  that  gives  promise  of  success 
in  any  considerable  variety  of  the  cases.  There  should  be  strict 
inquiry  as  to  the  patient's  habits  of  cleaning  the  teeth  in  every 
case,  and  the  use  of  any  tooth  powders  whatever  prohibited. 
A  sufBcient  use  of  clear  water  and  the  brush  will,  I  believe,  do  no 
harm.  In  what  I  learned  of  Dr.  Miller's  work  in  the  production 
of  erosion  it  seemed  to  me  that  he  was  not  very  successful  in 
producing  erosion  with  the  brush  and  water,  even  when  much 
brushing  was  done  with  the  electric  motor.  With  the  powders, 
however,  the  teeth  were  worn  away.  He  also  found  sharp  grit 
in  many  of  the  tooth  powders  in  use.  The  brush  used  with  water 
regularly  and  sufiBciently,  but  with  moderation,  will  certainly 
keep  the  teeth  in  good  condition  as  to  cleanliness.  If  many 
dentists  will  do  this  and  report  the  results  carefully  as  to  the 
effect  on  the  progress  of  the  erosion,  we  will  soon  gain  valuable 
clinical  evidence  as  to  the  possible  effect  of  the  brush  with  and 
without  abrasive  powders.  Those  who  have  connected  erosion 
with  the  gouty  diathesis  have  made  some  effort  for  the  relief 
of  the  general  condition  with  the  hope  that  the  progress  of  the 
erosion  might  be  controlled,  but  thus  far  no  very  considerable 
benefits  have  been  reported. 

I  have  made  considerable  effort  to  reduce  the  evil  results 
by  inserting  fillings,  but  can  report  but  few  successes,  and  am 
now  of  the  opinion  that  some  of  these  apparent  successes  were 
due  to  a  coincident  spontaneous  stoppage  of  progress  of  the 
erosion,  rather  than  from  the  influence  of  the  fillings.  In  the  case 
illustrated  in  Figure  48, 1  filled  all  of  the  eroded  areas  with  gold, 
removing  all  that  remained  of  the  labial  and  buccal  surfaces. 
This  was  effective  for  the  teeth  so  treated,  and  fortunately  the 
erosion  did  not  spread  to  other  teeth.  I  saw  the  case  occasionally 
until  the  patient  died,  about  fifteen  years  later.  This  was  done 
before  the  modem  process  of  porcelain  crowns  had  become  suc- 
cessful. The  treatment  was  simply  horrible  from  the  esthetic 
standpoint,  but  it  gave  the  patient  the  full  use  of  her  teeth  with 
perfect  comfort  for  the  remainder  of  her  life. 

In  my  efforts  filling  has  been  of  no  other  value  except  to 
limit  sensitiveness  and  depth  of  cutting,  unless  all  of  the  surface 
being  eroded  was  removed,  except  possibly  in  some  of  the  nar- 
row cross  cuttings  and  a  few  of  the  wedge-shaped  areas.    The 


58  PATHOLOGY    OF    THE    HABD    TISSUES    OF    THE    TEETH. 

erosion  will  go  on  beside  the  fillings  and  continue  spreading, 
leaving  the  margins  of  the  fillings  standing  as  they  were  placed. 

One  who  has  had  a  wide  observation  of  erosion  and  of  its 
progress  from  year  to  year  may  do  much  good  by  filling  in 
certain  selected  cases.  These  should  be  those  deep  cuts  across 
the  teeth  that  show  little  or  no  disposition  to  lateral  spreading. 
In  a  number  of  cases  of  this  character  I  have  cut  the  groove 
fully  to  the  mesial  and  distal  surfaces,  and  filled  them  with  gold 
without  other  preparation.  These  have  generally  been  success- 
ful. Early  in  my  work  I  filled  two  of  these  without  the  exten- 
sion mentioned.  The  erosion  soon  made  the  extension,  and 
refilling  became  necessary.  These  include  very  few  of  the  cases. 
The  wedge-shaped  forms  have  in  a  few  instances  done  well  with 
fillings,  and  certainly  the  depth  of  the  cutting  can  be  materially 
limited.  Most  of  my  efforts  with  these,  however,  have  failed 
to  stop  the  spreading.  With  the  dish  forms  I  have  seen  no  suc- 
cess short  of  cutting  away  the  remainder  of  the  labial  surface 
and  replacing  it.  The  artificial  crown  is  the  better  treatment. 
In  other  forms  of  cutting,  filling  seems  to  be  of  no  use  except 
to  limit  the  sensitiveness  for  a  considerable  time,  and  to  prevent 
depth.  The  filling  may  be  done  with  porcelain  inlays  when  that 
seems  desirable.  In  the  great  majority  of  cases,  however,  it 
will  be  better  not  to  make  fillings  of  any  kind. 

I  am  therefore  of  the  opinion  that,  as  a  general  rule,  fillings 
should  not  be  made  in  the  treatment  of  erosion.  That  which 
now  promises  the  best  results  is  to  keep  watch  of  the  cases,  and 
at  the  proper  time  cut  away  the  remaining  parts  of  the  crowns 
and  place  artificial  crowns. 

The  sensitiveness  when  very  annoying  may  be  relieved, 
temporarily  at  least,  by  severe  burnishing.  The  best  way  to  do 
this  is  with  the  burnisher  cut  in  ridges  something  like  a  coarse 
cut  bur,  with  the  edges  rounded  and  polished.  Some  use  has 
been  made  of  these  for  burnishing  fillings.  Place  the  bur  on  the 
eroded  and  sensitive  surface  while  rapidly  rotating,  and  go  over 
its  surface  quickly  with  strong  pressure.  Repeat  this  several 
times  and  then  leave  it  alone.  The  first  application  will  cause 
sharp  pain  momentarily,  but  afterward  there  will  be  less,  or  no 
pain.  This  will  generally  relieve  the  sensitiveness  for  some 
time.    This  may  be  repeated  when  necessary. 

When  erosion  has  progressed  so  far  that  the  teeth  have 
become  much  disfigured,  the  crowns  should  be  cut  away  and  por- 
celain crowns  of  some  form  substituted.  These,  if  well  made, 
will  give  excellent  service. 


EBOSION   OP   THE   TEETH.  59 

In  watching  the  progress  of  many  cases  of  erosion  a  rather 
large  number  will  be  fomid  that  become  stationary  without 
known  cause,  and  so  remain  indefinitely.  These  cases  will,  of 
course,  vitiate  many  of  the  supposed  good  results  of  treatment 
by  filling,  or  any  form  of  treatment  intended  to  limit  or  to  stop 
the  progress  of  erosion. 


60  PATHOLOGY   OF    THE    HAED    TISSUES    OF    THE   TEETH. 


CARIES  OF  THE  TEETH, 

Historical. 

MORE  or  less  vague  writings  of  caries  of  the  teeth  are  found 
in  ancient  literature,  most  of  which  are  too  uncertain  in 
their  meaning  for  us  to  gain  any  clear  conception  of  the  views 
held  of  its  cause.  Other  writings  of  the  specialties  in  medicine, 
such  as  the  mention  of  physicians  for  the  teeth,  extraction  of 
teeth  and  of  artificial  teeth  are  not  of  interest  in  this  connection. 
Close  studies  of  the  conditions  surrounding  the  beginning  and 
progress  of  dental  caries  have  developed  very  slowly.  The 
oldest  writing  that  I  know  which  attempts  a  rational  presenta- 
tion of  the  cause  of  dental  caries  is  by  an  anonymous  author  in 
the  German  language  in  1530.  I  present  here  a  photographic 
reproduction  of  a  single  paragraph. 

ttr  $en  wenn  fic  lS<i)exiQt  vuty  ^ol  toerbc 
i»elci)6am  meiftmt>en  bof^^enc  Qcfd)id)b 
v^mcmi<$U(i)m  fo  emer  ifi  mnt>  fie  iiic^t 
vm  bey  an^anQc^e  fpejifc  mmQetlweld)& 
fanl  wir&t/  vnt>  mad)tt>AYn(xd)  bSfc  fd}i 
Mffe  fettd^ti^ieit  bie  fie  aite  friff  »rt  cgct/ 
ion^  ^mmcr  (}(l  mcltct)  vbtxlj/ant  tv^mmct 
baf6ftemd)Q<mtivnt>tt(trt>ieim  Berber 
bet/vnnt>  K>ama(i)nia)tam  fc^mensen 

The  statement  is  remarkable  for  its  close  agreement  in 
substance  to  the  views  now  held,  if  stated  without  detail.  The 
wording  is  very  quaint  and  in  some  unessential  points  the  mean- 
ing is  uncertain.    I  should  translate  it  thus : 

Translation.  Caries  is  a  disease  and  evil  of  the  teeth  in 
which  they  become  full  of  holes  and  hollow,  which  most  often 
affects  the  back  teeth;  especially  so  when  they  are  not  cleaned  of 
clinging  particles  of  food  which  decompose,  producing  an  acid 


CABIES   OF   THE   TEETH.  61 

moisture  (literally,  a  sharp  moisture)  which  eats  them  away  and 
destroys  them  so  that  finally  with  much  pain  they  rot  away  little 
by  little. 

In  the  same  volume  this  writer  gives  also  the  oldest  authentic 
mention  of  the  use  of  gold  for  filling  teeth.  The  paragraph  runs 
thus: 

Sumtn'teeM  b<ts  mm  bte<tti6^oIfljf8 
toe^t  mmtmtlvcdd}$  md)  <j»f jweycil^ 
i»c"^|e  gcfd^tc^t/  gum  ex^m  tiOQ  mm  t^aa 
hd)  vnt>  Ue  rtti  je^efllmgc  mit  emtm  pib^ 
tikn  mciffcld>enrtbermeffcrci)cit\))aw[)c/ 
rtbcr  miuimm  anttctti  injimmmttf^ir^u 
i)cqucmfcFItd)/tt3ege  \<i)Abe/vn^  vdnisel 
aU  t)'?  pvacUctanten  tvol  m{\enlvnb  txtv 
3M  cr^rtlbung  t>c8  an^exn  te'jlee  tee  ^anee 
tMs  wd)U(i)m  mt'e  golt  hlettcvn  yn  fiiUec» 
^um  <jrtbembrtsm«tt»tgebr4U(^ccrQtc^ 
t)AYin^mli(i)roclcl)6Qefd)ictmU^  (Bidlea 
epffel  vnD  tvtioer  Sd%en  fo  ber  san  md) 
fccr  m'tttguitg  Ortrmtt;  wir^t  gtfiiUec 

The  following  is  very  nearly  its  meaning.  The  writer  is 
discussing  plans  of  treatment  of  caries. 

Tbanslation.  In  the  third  plan,  the  hollow  place  is  done 
away  with  (taken  away  —  removed)  which  is  done  in  one  of  two 
ways.  First,  the  soft  part  of  the  cavity  and  the  decayed  part 
is  cut  away  with  small  chisels,  knives,  files  or  other  suitable 
instruments,  and  cleaned,  as  is  well  known  to  practitioners. 
Then  for  the  saving  of  the  remaining  parts  of  the  tooth,  the 
cavity  is  filled  with  gold  leaf.  Otherwise  one  may  use  a  suit- 
able gum  prepared  with  nutgalls  and  hyssop  to  fill  the  cavity 
after  cleaning  it. 

This  writer  mentions  Mesu  as  an  authority,  a  man  who 
lived  some  two  hundred  years  earlier,  who  is  also  mentioned 
by  other  writers,  but  so  far  as  is  now  known,  none  of  his  writings 
have  been  preserved. 

The  French  writings  in  dentistry  are  older  than  the  English, 
but  do  not  contain  very  clenr  statements  of  view  of  the  pathology 
of  caries.  Generally  the  statements  are  equivalent  to  saying 
the  teeth  rot  away  or  decay  away,  without  attempt  of  esplana- 
tion  of  the  process. 


62  PATHOLOGY    OF    THE    HABD    TISSUES    OF    THE   TEETH. 

Fouchard  wrote  in  French  in  1728  and  a  translation  was 
made  into  German  by  Augustine  Duddei  in  1733.  Second  and 
third  editions  were  published  in  French  in  1746  and  1786.  In 
none  of  these  is  there  any  statement  regarding  the  cause  of  den- 
tal caries  that  is  as  definite  in  conception  as  the  one  quoted 
above.  This  seems  to  be  true  of  all  of  the  writings  of  that  time. 
Fouchard  mentions  filling  carious  cavities  with  gold,  but  con- 
demns the  practice  apparently  because  of  the  expense,  and 
because  certain  persons  of  evil  disposition  deceived  the  people 
by  using  tin  so  prepared  as  to  appear  like  gold.  As  filling 
materials,  he  preferred  lead  or  tin  leaf  (foil). 

John  Hunter,  writing  in  English  (1778),  expresses  very 
clearly  a  different  view,  in  which  he  says :  ' '  The  most  common 
disease  to  which  the  teeth  are  exposed  is  such  a  decay  as  would 
appear  to  deserve  the  name  of  mortification,"  with  which  he 
expresses  some  dissatisfaction  as  being  an  incomplete  explana- 
tion of  the  diseased  process.  This,  with  other  writings  by  the 
same  author,  shows  that  in  considering  the  diseases  of  the  teeth 
he  was  following  closely  the  lines  of  thought  of  his  time  of  what 
we  now  know  as  necrosis  of  bones. 

Fox  (1806)  expresses  a  similar  view,  which,  with  slight  mod- 
ification, was  repeated  by  Bell  (1825),  who  proposed  the  term 
' '  dental  gangrene ' '  to  take  the  place  of  the  more  common  terms 
"decay"  or  "caries." 

This  seems  to  have  been  the  most  common  view  of  medical 
men  of  that  time,  and,  with  slight  modifications,  was  repeated 
by  most  writers.  All  of  these  men  regarded  caries  of  the  teeth 
as  being  a  result  of  inflammation  and  as  beginning  within  the 
dentin  instead  of  upon  the  surface  of  the  enamel.  Koeker  of 
Philadelphia  (1830)  speaks  of  decay  penetrating  the  enamel 
from  within  outward,  saying  that  it  "had  thus  formed  a  natural 
outlet  for  the  bony  abscess." 

Robertson  (1835)  expresses  a  different  view,  which,  in  its 
main  features,  agrees  substantially  with  the  earlier  views  of  the 
anonymous  author  quoted  above.  But  Robertson  is  more  explicit 
in  the  detail.  According  to  this  view,  caries  of  the  teeth  resulted 
from  the  action  of  an  acid  generated  by  the  decomposition  of 
food  particles  or  fluids,  which  lodged  at  particular  points  about 
the  teeth  and  dissolved  out  the  calcium  salts  of  which  the  teeth 
are  composed.  These  points  of  lodgment  were  shown  to  be  the 
points  at  which  caries  made  its  beginning,  as  in  pits  and  deep 
grooves  in  the  occlusal  surfaces,  between  the  teeth  (proximal 
surfaces)  or  about  the  margins  of  the  gums. 


OABIES   OF   THE    TEETH.  63 

Regnard  of  Paris  (1838)  defined  caries  of  the  teeth  as 
"destruction  of  the  teeth  by  decomposition."  His  contention 
was  that  this  destruction  took  place  at  the  very  spot  where  the 
acid  was  formed,  or  where  the  alimentary  particles  lodged  and 
decomposed. 

This  was  called  the  chemical  theory  of  caries  of  the  teeth. 
A  large  body  of  dentists,  both  in  Europe  and  America,  gave  simi- 
lar expressions  of  view  at  about  this  time.  The  idea  that  inflam- 
mation of  the  dentin  had  any  part  in  its  causation  was  denied. 
Also  the  statements  of  Fox,  Bell,  and  many  others,  that  caries 
began  within  the  dentin  and  worked  its  way  outward,  were  gen- 
erally denied.  Instead,  it  was  asserted  that  caries  always  began 
upon  the  surface  of  the  tooth,  or  in  pits,  fissures,  etc.,  that  were 
open  to  the  surface.  The  contentions  along  these  differences 
of  thought  were  sharp  and  the  lines  closely  drawn.  This  brought 
about  a  much  closer  observation  and  study  of  the  nature  and 
form  of  the  physical  injuries  inflicted  by  dental  caries,  and  with 
this,  the  opinion  became  general  that  caries  always  began  on  the 
outside  of  the  tooth  and  worked  its  way  inward,  forming  a  cavity. 
During  this  period  also,  comparative  anatomists  and  geologists 
were  studying  closely  the  teeth  of  the  living  animals  and  those 
remaining  of  extinct  animals,  in  which  prominent  differences 
between  the  structure  of  the  teeth  and  the  bones  were  ascer- 
tained. Owen  gave  us  the  word  "dentin,"  distinguishing  that 
which  had  before  been  called  tooth  bone  from  true  bone. 

A  knowledge  of  histology  began  to  be  developed.  The  cell 
theory  of  the  construction  of  organic  bodies,  animal  and  vege- 
table, was  propoimded  and  rapidly  assumed  the  general  form 
in  which  it  stands  at  the  present  time.  Makers  of  microscope 
lenses  rapidly  improved  them  because  of  the  encouragement  and 
patronage  induced  by  these  studies.  In  the  midst  of  this,  John 
Tomes,  of  London,  was  studying  the  microscopic  structure  —  the 
histology  —  of  the  teeth  and  bones,  and  by  1860  this  was  devel- 
oped almost  completely  as  it  stands  to-day.  It  is  true  that  since 
then  much  more  exactness  of  method  and  greater  accuracy  of 
detail  has  been  added.  But  the  full  foundation  of  our  knowledge 
of  dental  histology  and  the  development  of  the  teeth  was  laid  by 
John  Tomes. 

It  seems  that  Mr.  Tomes  began  this  work  with  the  inflam- 
matory theory  of  caries  strongly  fixed  in  his  mind.  He  found, 
however,  that  inflammation  could  not  take  place  in  the  teeth. 
The  histological  structure  of  the  teeth  was  such  that  there  was 
no  provision  for  the  circulation  of  blood  in  the  dentin,  neither 


64  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

was  there  any  provision  for  processes  of  repair  of  injuries.  Yet 
the  dentin  was  a  vital  tissue  and  it  was  the  opinion  of  Mr.  Tomes 
that  this  vitality  must  be  destroyed  before  the  part  could  bo 
dissolved  out  by  an  acid,  thus  forming  a  cavity.  He  admitted, 
however,  that  the  same  agent  —  an  acid  —  might  do  both.  This 
gave  rise  to  the  chemico-vital  theory  of  dental  caries,  which  was 
much  discussed  from  1840  to  1880. 

Finally  Dr.  Magitot  of  Paris  (English  translation,  1878) 
published  the  most  extensive  work  that  has  been  produced  on 
this  subject,  detailing  much  experimentation  in  various  ways 
in  the  endeavor  to  determine  the  exact  cause  of  the  disease.  His 
conclusions  were  that  caries  of  the  teeth  was  produced  purely  by 
chemical  substances  developed  in  the  mouth  or  introduced  with 
food.  This  work  seemed,  for  the  time  being,  to  establish  the 
purely  chemical  theory  of  the  production  of  dental  caries. 

In  the  meantime,  there  had  been  many  suggestions  that 
microorganisms  might  be  found  to  play  a  prominent  part  in  the 
production  of  dental  caries.  The  first  important  work  published 
on  this  subject  was  by  Leber  and  Kottenstein  (German  1867  — 
English  translation,  1868)  in  which  these  authors  claimed  to 
have  determined  the  presence  of  these  fungi  in  the  dentinal 
tubules  (which  were  much  enlarged)  of  carious  areas.  Strong 
corroborative  evidence  of  the  correctness  of  their  view  existed 
in  the  fact  that  John  Tomes  had  determined  previously  that  the 
tubules  in  carious  areas  were  constantly  much  enlarged  and 
filled  with  granules,  the  nature  of  which  he  could  not  determine. 
This  observation  by  Mr.  Tomes  had  been  confirmed  by  the  obser- 
vation of  others  and  had  become  fixed  as  an  essential  difference 
between  dental  caries  and  a  simple  solution  of  the  calcium  salts 
of  a  tooth  by  an  acid.  Still,  the  work  of  Leber  and  Eottenstein 
made  no  considerable  impression  on  the  opinions  held  by  den- 
tists. These  gentlemen  wrote  before  the  development  of  the 
staining  methods  by  anilin  dyes,  which  certainly  distinguish 
microorganisms  in  tissues.  Neither  were  they  able,  by  means 
of  culture  methods  then  known,  to  separate  microorganisms  into 
distinct  species  and  determine  the  character  of  each  as  to  its 
power  of  producing  fermentation  or  other  special  forms  of 
decomposition. 

Miles  and  Underwood  of  London  (1881)  determined  defi- 
nitely that  the  enlarged  tubules  in  dental  caries  contained  micro- 
organisms, by  use  of  the  anilin  dyes  discovered  by  Dr.  Koch, 
the  German  bacteriologist,  but  they  were  unable  to  go  farther 
for  the  lack  of  better  facilities  for  division  of  species  of  micro- 


CABIES   OF   THE   TEETH.  65 

organisms  and  the  determination  of  their  physiological  charac- 
ters in  the  production  of  fermentations  or  putrefactions. 

Dr.  W.  D.  Miller  was  at  work  with  Dr.  Koch  in  his  bacteri- 
ological laboratory  when  the  means  of  cultivating  microorgan- 
isms on  semi-solid  media  was  first  established  and  was  at  once 
able  to  separate  the  microorganisms  found  in  the  mouth  or  in 
carious  dentin  into  species,  and  determine  the  character  of  each 
in  the  production  of  acid  fermentation  or  other  forms  of  decom- 
position. The  finding  in  the  dentinal  tubules  of  microorganisms 
which,  when  growing  in  artificial  culture  in  the  presence  of  any 
form  of  sugar  or  starch,  uniformly  produced  lactic  acid,  which 
in  time  dissolved  the  calcium  salts  of  the  tooth  tissue,  completed 
the  full  explanation  of  the  local  changes  taking  place  in  caries 
of  dentin,  but  the  cause  and  the  nature  of  caries  of  enamel  was 
not  so  clearly  made  out. 

This  history,  briefly  as  it  is  written  here,  shows  the  principal 
steps  of  the  unfolding  of  a  knowledge  of  this  disease  process 
extending  through  many  years  of  labor  done  by  many  individ- 
uals, each  building  upon  the  discoveries  which  were  made  by 
his  predecessors.  The  outcome  of  this  work  has  finally  given 
complete  and  exact  knowledge  of  the  steps  in  caries  of  dentin. 
It  will  also  be  seen  that  the  work  of  Dr.  Miller  was  really  the 
finding  of  the  exact  method  of  the  formation  of  the  acids  which 
the  older  anonymous  German  writer  (1530),  Eobertson  (1835), 
Regnard  (1838),  and  others,  described  as  being  formed  by 
decomposition.  This  brief  summary  mentions  the  work  of  but 
a  few  of  the  men  who  seem  to  have  been  most  fortimate  in  the 
finding  and  giving  expression  to  facts  that  have  advanced  our 
knowledge  of  the  processes  taking  place  in  caries  of  the  teeth. 
As  a  matter  of  fact,  many  men  have  taken  part  in  this  work. 

GrENERAi,  Statement. 

Caeies  in  its  simplest  expression  consists  in  a  chemical  dis- 
solution of  the  calcium  salts  of  the  tooth  by  lactic  acid,  followed 
by  the  decomposition  of  the  organic  matrix,  or  gelatinous  body, 
which,  in  the  dentin,  is  left  after  the  solution  of  the  calcimn  salts. 
In  caries  of  the  enamel,  the  whole  substance  of  the  tissue  is 
removed  by  dissolving  out  the  calcium  salts,  there  being  so  little 
organic  matrix  in  the  enamel  that  it  will  not  hang  together; 
consequently  a  cavity  is  formed  by  the  simple  solution  of  the 
calcium  salts  of  which  it  is  composed.  This  solution  always 
begins  upon  the  surface,  never  in  the  interior.  Decay  of  the 
teeth  is  therefore  caused  by  an  agent  acting  from  without  the 
8 


66  PATHOLOGY   OF    THE    HARD    TISSUES    OF    THE    TEETH. 

tootli,  never  from  witliin  tlie  tooth.  It  is  something  extraneous 
to  the  tooth,  acting  upon  the  surface  in  the  beginning  and  pene- 
trating little  by  little  into  its  substance. 

Caries  of  the  dentin  is  different  from  caries  of  the  enamel, 
in  that  the  organic  matrix  is  sufficient  in  amount  and  consistence 
to  retain  its  histological  and  physical  forms  after  the  solution 
and  removal  of  the  calcium  salts.  With  the  removal  of  these 
by  an  acid,  the  enamel  will  have  disappeared  entirely,  but  the 
dentin  will  not  suffer  any  change  of  form.  Therefore,  the  simple 
solution  of  the  calcium  salts  leaves  a  softened  matrix  in  the 
dentin  and  does  not  form  a  cavity.  After  the  solution  of  the 
calcium  salts,  there  is  a  decomposition  of  this  organic  matrix 
progressing  from  without  inward,  breaking  it  up  and  finally 
forming  a  cavity.  Between  the  solution  of  the  calcium  salts  and 
the  decomposition  of  the  organic  matrix,  some  little  time  passes. 
The  two  seem  never  to  occur  at  the  same  time  in  any  given  por- 
tion of  the  tooth,  but  the  calcium  salts  are  dissolved  out  first 
and  the  decomposition  of  the  organic  matrix  follows  later. 
Therefore,  while,  after  the  full  development  of  the  carious  proc- 
ess, both  may  be  progressing  at  the  same  time,  the  solution  of 
the  calcium  salts  is  always  considerably  in  advance  of  the  decom- 
position of  the  organic  matrix,  leaving  a  zone  of  softened  mate- 
rial between. 

In  the  progress  of  the  solution  of  the  calcium  salts  of  the 
dentin,  the  tendency  is  to  spread  in  every  direction  from  the 
point  of  penetration  of  the  enamel,  and  especially  along  the 
dento-enamel  junction.  Then,  particularly  when  the  original 
opening  in  the  enamel  has  been  small,  the  enlargement  of  the 
opening  is  brought  about  mostly  by  what  is  termed  "backward 
decay  of  the  enamel."  This  is  decay  of  the  inner  surface  of 
the  enamel  that  is  in  contact  with  the  decaying  dentin  under  it, 
due  to  the  spreading  just  mentioned.  In  this  case  the  enamel 
decays  from  the  inside  outward  until  it  is  so  weakened  that  it 
breaks  away,  enlarging  the  opening.  The  rapidity  of  this  back- 
ward decay  of  the  enamel  is  exceedingly  variable.  Cavities 
may  be  wide  open  early  in  their  progress,  or  they  may  remain 
for  a  considerable  time  with  a  small  opening. 

The  calcium  salts  are  not  dissolved  complete  from  without 
inward  in  the  first  instance,  but  the  acid  which  dissolves  them 
seems  to  spread,  or  percolate,  into  the  tissue  and  the  solution 
goes  on  as  a  gradual  softening  process.  The  innermost  part 
affected  is  less  softened  than  tlie  more  superficial  parts.  In  the 
outer  portion  of  the  softening  area  all,  or  about  all,  of  the  cal- 


CABIES   OF    THE    TEETH.  67 

cium  salts  have  been  dissolved,  while  in  the  inner  portion  but 
very  little  is  yet  dissolved.  In  this  way  the  action  of  the  acid 
progresses  slowly  from  without  inward. 

The  decomposition  of  the  organic  matrix  of  the  dentin  pro- 
gresses in  a  similar  way,  the  tissue  being  broken  up  little  by 
little  progressively,  from  without  inward,  so  that  the  formation 
of  a  cavity,  especially  when  the  opening  through  the  enamel  is 
small,  follows  slowly  the  solution  of  the  calcium  salts.  There- 
fore, it  often  happens  that  the  solution  of  the  calcium  salts  has 
progressed  much  more  rapidly  than  the  decomposition  of  the 
organic  matrix.  In  that  case,  we  find  a  very  large  amount  of 
material  that  is  soft  and  spongy,  which  may  be  easily  cut  with 
a  sharp  excavator;  or,  after  removing  any  overlapping  enamel 
that  may  interfere,  a  spoon  excavator  may  be  passed  along  the 
margin  of  the  decayed  area,  and  the  whole  of  it  may  be  turned 
out  in  a  body,  soft  enough  to  be  cut  with  a  razor  or  sharp  knife. 
Occasionally  we  will  see  almost  the  entire  interior  of  the  enamel 
cap,  i.  e.,  almost  the  entire  dentin  of  the  crown  of  the  tooth, 
softened  in  this  way  and  yet  the  organic  matrix  is  not  yet  broken 
up.  This,  however,  is  the  exception  to  the  rule.  The  general 
rule  is  that  the  decomposition  of  the  organic  matrix  follows 
fairly  closely  the  removal  of  the  calcium  salts. 


68  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE   TEETH. 

CAEIES  OF  DENTIN. 

ILLUSTRATIONS:    FIGURES  63-74. 

Althougli  in  the  natural  order  of  the  phenomena,  caries  of 
enamel  always  precedes  caries  of  dentin,  it  is  preferred  to  first 
describe  caries  of  dentin  for  the  reason  that  the  order  and  char- 
acter of  the  processes  in  its  progress  are  regarded  as  having 
been  completely  made  out,  and  it  is  believed  that  afterward 
caries  of  enamel  will  be  easier  understood.  It  is  sufficient  here 
to  say  that  caries  of  dentin  can  not  occur  until  the  enamel  has 
been  penetrated.  The  enamel  with  its  rods  cemented  together 
by  its  cementing  substance  is  a  solid.  It  has  no  natural  open- 
ings into  which  microorganisms  can  grow,  and  these  have  no 
power  of  penetrating  into  it,  except  as  it  is  dissolved  and 
removed  by  the  acids  which  they  form  during  their  growth. 
Therefore,  in  decay  of  the  enamel,  the  microorganisms  producing 
the  acid  are  on  its  surface.  On  the  other  hand,  the  dentin  is 
everywhere  permeated  by  the  dentinal  canals  into  which  micro- 
organisms may  grow  when  the  dentin  is  exposed  by  the  destruc- 
tion of  the  enamel. 

Both  caries  of  enamel  and  caries  of  dentin  are  caused  by 
the  same  agency;  namely,  the  growth  of  microorganisms  in 
contact  with  the  surface  of  the  enamel  in  the  first  instance,  and 
the  formation  of  lactic  acid  during  that  growth,  which  dissolves 
the  calcium  salts  of  which  it  —  the  enamel  —  is  composed.  In 
caries  of  dentin,  the  microorganisms  grow  into  the  dentinal 
tubules  and  form  their  acid  product  within  the  tissue  itself.  This 
dissolves  the  calcium  salts  of  the  dentin,  converting  it  into  the 
soluble  salt,  calcium  lactate,  which  gradually  escapes  into  the 
surrounding  saliva  by  osmosis. 

Osmosis.  The  word  osmosis,  as  used  here,  is  used  in  phys- 
ical chemistry  to  represent  the  passage  of  soluble  salts  through 
animal  membranes.  This  occurs  whenever  a  fluid  containing  the 
specified  salt  is  in  contact  with  the  membrane  upon  the  one  side 
and  water  is  in  contact  with  the  same  membrane  upon  the  other 
side.  In  this  case,  the  salt  will  pass  through  the  membrane 
into  the  water  until  the  water  on  either  side  of  the  membrane 
becomes  equally  salt.  Or  again,  if  two  salts,  which  will  commingle 
in  solution  without  chemical  reaction,  are  placed  in  solution  in 
water  separately,  and  the  one  placed  in  contact  with  one  side  of 
a  membrane  and  the  other  in  contact  with  the  other  side  of  the 


Fia.   63. 


Fia.   64. 


Figs.  63,  64.  Photographs,  very  nearly  full  size,  of  a  small  dialyzer  used  for  separating  the  salts 
from  the  saliva,  or  other  body  fluids,  for  the  microscopic  study  of  the  crystals.  With  this,  it  is  the  inten- 
tion to  deal  with  very  small  volumes.  In  Figure  63  the  parts  of  the  piece  of  apparatus  are  in  position. 
In  Figure  64  the  lid  with  the  tube  passing  through  it  is  removed  and  laid  to  one  side.  The  tube  passing 
through  the  lid  has  a  small  rubber  band  around  it  above  the  lid,  which  may  be  moved  to  hold  the  tube 
at  any  height  above  the  bottom  of  the  vessel.  The  lower  end  of  the  tube  is  closed  with  a  piece  of  gold- 
beaters' skin  stretched  over  it  and  tied  with  a  thread.  This  may  have  a  coating  of  collodion  to  close 
any  possible  opening.  A  piece  of  fresh  bladder  could  be  used  as  well.  In  use,  the  saliva  or  other  body 
fluid  is  placed  in  the  dish  and  about  two  cubic  centimeters  of  distilled  water  are  placed  in  the  tube 
and  the  height  of  the  tube  adjusted  so  that  the  surface  of  the  water  in  it  will  be  about  level  with  the 
top  of  the  fluid  in  the  disli.  Devised  and  first  used  for  this  purpose  by  Dr.  Edward  C.  Kirk.  Tliis 
dialyzer  was  presented  to  the  author  by  Dr.   Kirk. 


Fio.    65. 


Fla.   65.     A  photomicrograph  of  salts  dial.vzed  from  the  saliv.i  and  crystallized  on   a  cover  glass. 
Only  a  minute  drop  of  fluid  was  used. 

Fin.  66.     Crystals  of  sugar.     A  photomicrograph  with  polarized  light. 


Fig.   6S- 


Fig.  69. 


Fig. 


Fig.  67.  A  bicuspid  split  mesio-distally  through  an  area  of  decay  and  photographed  before  sepa- 
rating the  halves.  When  these  are  opened  like  a  hook,  the  penetration  of  the  decay  will  be  disclosed. 
These  cuts  have  been  made  for  the  illustrations  in  an  especially  arranged  lathe,  in  which  the  tooth  is 
mounted  on  a  slide  rest.  The  cutting  is  done  with  a  rapidly  revolving  aluminum  disk,  twenty-six  gauge 
(thirty-two  gauge  may  be  used)  charged  with  carbonmdum  powder  mixed  with  soapy  water.  With 
this,  slices  1-100  of  an  inch  thick  may  be  cut. 

Fio.  68.  The  occlusal  surface  of  an  upper  first  molar  with  a  decay  in  the  central  pit.  This  tooth 
was  split  mesio-distally  and  is  shown  in  Figure  71. 

Figs.  69,  70.     Other  upper  first  molars  showing,  apparently,  similar  decays. 


FiQ.   71. 


Fia.  72. 


Fio.  71.  The  upper  first  molar,  Figure  68,  split  mesio-distally,  the  surfaces  polished,  laid  open  and 
photographed  to  show  the  penetration  of  decay.  The  specimen  shows  particularly  well  the  typical 
conical  form  of  the  penetration  of  dentin  as  it  occurs  when  the  opening  in  the  enamel  remains  small. 
It  also  shows  well  the  spreading  of  decay  along  the  dento-cnamel  junction  of  the  occlusal  surface  form- 
ing the  broad  base  of  the  cone  of  the  area  of  decay. 

FlQ.  72.  A  lower  second  molar  with  a  large  area  of  decay  which  has  begim  in  the  buccal  pit. 
The  decay  has  spread  along  the  dento-enamel  junction,  undermining  the  greater  part  of  the  enamel  of 
the  buccal  half  of  the  tooth  and  has  destroyed  nearly  one-half  of  the  dentin.  This  injury  has  occurred 
while  the  opening  into  the  cavity  has  remained  small. 


GABIES   OF   DENTIN.  69 

same  membrane,  the  two  salts  will  pass  through  the  membrane 
in  opposite  directions  until  they  have  become  equalized  in  the 
two  solutions.  This  process,  when  used  to  separate  crystallizable 
salts  from  colloid  substances  with  which  they  may  be  com- 
mingled, is  known  as  dialysis,  for  it  is  found  that  such  substances 
as  gums,  resins,  albumens,  etc.,  which  are  not  crystallizable,  do 
not  readily  pass  through  membranes  in  this  way.  Therefore, 
if  there  is  a  solution  of  sugar  in  the  saliva  and  a  solution  of 
calcium  lactate  in  the  depths  of  a  carious  cavity,  that  part  of 
the  matrix  of  the  dentin  which  is  already  softened  by  the  solu- 
tion of  its  calcium  salts,  acts  as  a  dialyzing  membrane,  passing 
the  sugar  in  and  calcium  lactate  out.  In  this  way,  the  growing 
microorganisms  receive  sugar  from  the  saliva,  and  lactic  acid 
(their  waste  product)  which  has  become  calcium  lactate  by  com- 
bination with  the  calcium  salts  of  the  tooth,  is  eliminated.  This 
process  naturally  goes  on  very  slowly,  so  that  weeks  and  months 
are  required  for  any  considerable  cavity  to  form,  and  often 
several  years.  Figures  63  and  64  represent  a  dialyzer  used  to 
obtain  salts  from  the  secretions  free  from  the  gummy  substances 
with  which  they  are  associated,  for  microscopic  examination 
of  their  crystals.  Figure  65  is  a  photomicrograph  of  the  salts 
dialyzed  from  saliva  and  crystallized.  Figure  66  is  a  photo- 
micrograph, made  by  polarized  light,  of  sugar  dialyzed  from  a 
solution  and  crystallized. 

In  penetrating  into  dentin  microorganisms  follow  the  den- 
tinal tubules,  simply  growing  into  them  as  a  grapevine  would 
grow  through  a  lattice.  The  anastomosing  loops  from  tubule  to 
tubule,  which  are  plentiful  near  the  dento-enamel  junction,  and 
any  other  openings  such  as  interglobular  spaces  which  they 
may  encounter,  are  tilled  full  as  they  go.  There  is  much  dif- 
ference found  in  different  teeth  in  the  number  and  size  of  the 
anastomosing  loops  from  tubule  to  tubule.  In  some  these  are 
plentiful,  in  others  very  much  limited.  In  all,  however,  there 
is  a  sufficient  number  of  these  near  the  dento-enamel  junction 
to  afford  a  moderately  free  passage  of  microorganisms  from 
one  tubule  to  another.  In  a  considerable  proportion  of  teeth 
there  are  many  small  interglobular  spaces  along  next  to  the 
dento-enamel  junction,  known  as  the  "granular  layer  of  Tomes," 
through  which  microorganisms  may  readily  grow.  Therefore 
among  different  teeth  there  are  differences  in  the  facility  with 
which  microorganisms  will  spread  along  the  dento-enamel  junc- 
tion. The  organisms  having  gained  access  to  the  dentin  by  the 
solution  of  the  enamel,  they  grow  into  the  dentinal  tubules 


70  PATHOLOGY    OF    THE    HABD    TISSUES   OF    THE   TEETH. 

directly  toward  the  pulp.  They  are  continually  gaining  access 
to  other  tubules  by  spreading  laterally  along  the  dento-enamel 
junction  in  every  direction  from  the  first  point  of  entrance. 
Therefore,  the  tendency  is  to  the  formation  of  a  conical  area  of 
decay  ivith  the  point  of  the  cone  toward  the  pulp  of  the  tooth 
and  its  base  against  the  dento-enamel  junction.  The  breadth 
of  the  cavity  thus  formed,  in  relation  to  its  depth,  will  naturally 
depend  upon  the  comparative  rapidity  with  which  the  organisms 
may  spread  laterally  along  the  dento-enamel  junction.  For  this 
reason  some  cavities  are  broad  and  some  are  very  narrow  as 
compared  to,  their  depth. 

In  the  illustrations  of  this  subject  many  "split  teeth"  will 
be  used.  In  these  the  teeth  are  cut  through  the  decayed  area 
as  shown  in  Figure  67.  The  cut  surfaces  are  polished  and  the 
parts  laid  open  like  a  book  and  photographed  as  opaque  objects. 
The  half-tone  engravings  are  made  from  the  photographs  with- 
out any  retouching  whatever.  In  many  cases  only  one  of  the 
halves  has  been  used. 

The  form  taken  by  decay  in  dentin  when  it  has  begim  in  an 
occlusal  surface  is  well  shown  in  Figure  71,  a  photograph  from  a 
first  molar  split  in  half  mesio-distally  through  the  central  pit,  in 
which  the  decay  began.  The  occlusal  surface  of  the  tooth  before 
cutting  is  shown  in  Figure  68.  Other  photographs  of  molars 
showing  decays  which,  to  superficial  observation,  seem  to  be 
similar,  are  shown  in  Figures  69  and  70.  In  Figure  71  the  wide 
spreading  of  caries  along  the  dento-enamel  junction  forming  the 
base  of  the  cone,  and  the  point  of  the  cone  reaching  to  the  pulp 
chamber  are  well  shown.  This  is  the  most  common  form.  In 
this  case,  as  in  most  cases  of  split  teeth  displaying  caries,  the 
cut  surface  is  photographed  as  an  opaque  object.  In  examining 
such  illustrations,  it  must  be  remembered  that  a  section  through 
a  cone  gives  a  triangular  figure. 

Figure  72,  a  lower  second  molar  that  has  been  cut  bucco- 
lingually,  shows  a  decay  that  has  begun  in  the  buccal  pit.  This 
decay  has  proceeded  very  slowly.  There  is  the  same  wide  burrow- 
ing along  the  dento-enamel  junction  related  above,  and  the  effect 
of  the  continued  irritation  during  the  slow  progress  of  the  decay 
is  seen  in  the  reduction  of  the  size  of  the  pulp  chamber  by  the 
deposit  of  secondary  dentin.  This  condition,  resulting  from 
long  continued  irritation  of  the  dentinal  fibrils,  is  a  common 
effect.    It  occurs  also  in  abrasion  and  erosion. 

Careful  observation  has  shown  that  microorganisms  do  not 
begin  to  grow  into  the  dentinal  tubules  until  the  calcium  salts 


Fig.   73. 


Fig. 


Fig.  7;!.  An  iUnstratinn  sliowin;^  lln"  lilling  of  tin;  timl'iial  tubiilos  with  microorganisms.  The 
tUuiu  cnanM'l  jtini'lion  is  at  llu*  tup  cil  Ilio  illustration.  The  organisms  have  cntcri-tl  the  tubules  anil  hy 
continued  growth  and  multiplication  have  filled  and  enlarged  them  very  evenly,  liaving  grown  single 
tile  into  all  of  tiie  suiallor  siilo  branches.  Only  a  few  slight  local  swellings  of  tubules  are  seen.  The 
left  of  the  illustration  is  near  the  margin  of  the  invasion,  where  new  tubules  arc  as  yet  but  partially 
filled.  Great  ditTcrcnees  are  found  in  different  specimens  in  the  number  of  smaller  side  branches. 
Some  have  very  few  after  passing  a  little  way  from  the  dento-enamel  jimction. 

Fia.  74.  Another  illustration  of  the  filling  of  the  dentinal  tubuU-s  with  microorganisms,  in 
which,  as  compared  with  Figure  7;i,  the  opposite  extreme  as  to  side  br:\nches  and  irregular  swellings  of 
tlie  tubules  is  shown.  This  figuj-e  represents  something  liiie  a  niaxinunu  of  irregular  swellings  of 
tubules  and  with  no  side  branches.  This  is  taken  from  deeper  in  the  tooth  close  on  the  deeper  margin 
<if  the  invasion.  The  two  specimens  were  from  dilTerent  teeth,  and  hav<;  been  selected  as  representing 
the  extremes  of  smoothness  of  the  filling  and  enlargement  of  the  tubules  and  niaxinuun  of  filled  side 
branches,  as  seen  in  Figure  73  ;  and  absence  of  tilled  side  liranclies  and  something  near  the  maxinnim 
of  irregular  swellings  of  tubules,  as  seen  in  Figure  74.  All  gradations  between  these  two  illustrations 
are  found. 


CABIES   or   DENTIN.  71 

have  been  dissolved  out  for  some  little  distance  in  advance  of 
them.  In  the  natural  order  of  the  advatce  of  decay  this  is 
accomplished  in  the  beginning  by  the  percolation  of  acid  through 
the  enamel  before  the  enamel  rods  have  fallen  away,  so  as  to 
admit  microorganisms  to  the  dentin.  This  will  be  more  clearly 
shown  in  considering  caries  of  the  enamel.  Therefore,  when 
they  are  admitted  to  the  dentin,  some  portion  of  it  has  been 
softened  and  the  organisms  begin  growing  into  the  tubules  at 
once.  As  they  do  so  the  acid  which  they  are  forming  percolates 
into  the  dentin  in  advance,  dissolving  more  and  more  of  the 
calcium  salts.  In  this  way  it  happens  that  the  dentin  is  contin- 
ually softened  in  advance  of  the  growing  organisms  so  that 
there  is  a  little  space  softened  around  them  that  contains  none 
of  the  fimgi.  By  removing  all  overlapping  enamel  carefully 
to  give  good  opportunity,  a  thin,  sharp  spoon  excavator  may 
be  passed  closely  along  the  hard  dentin  at  the  margin  of  the 
softened  area  and  the  decayed  portion  turned  out,  removing 
with  it  practically  every  microorganism  in  the  dentin. 

As  the  microorganisms  fill  the  dentinal  tubules,  the  tendency 
is  to  become  more  and  more  crowded  together  and  the  tubules 
begin  to  be  enlarged.  In  some  cases  this  enlargement  is  a  very 
regular  increase  in  size  along  the  length  of  the  tubules,  the  outer 
ends  of  which  are  enlarged  most,  as  shown  in  Figure  73.  In 
other  cases  there  is  much  tendency  to  irregular  swellings  of  the 
tubules,  as  shown  in  Figure  74.  Indeed,  these  two  illustrations 
have  been  chosen  as  showing  the  extremes  of  regularity  and  of 
irregularity  in  this  respect.  Every  variation  between  the  two 
may  be  found.  Also  the  number  of  side  branches  into  which 
organisms  may  grow  varies  indefinitely;  after  passing  a  little 
way  from  the  dento-enamel  junction  some  cases  show  very  few 
or  even  none  at  all,  while  in  others  they  are  very  plentiful. 

This  enlargement  of  the  dentinal  tubules  contimies  until 
the  division  walls  disappear,  uniting  two  in  one,  three  into  one, 
and  so  on  until  there  is  nothing  left  but  a  mass  of  microorgan- 
isms mingled  with  some  undissolved  shreds  of  oi'ganic  matrix, 
which,  if  the  cavity  is  exposed  to  the  saliva,  wastes  out  and  is 
washed  away.  This  enlargement  of  the  tubules  and  destruc- 
tion of  the  organic  matrix  is  accomplished  by  the  enzjnne  of  the 
organisms.  It  is  digested.  Dr.  Miller,  in  his  examination  of 
this  point,  decalcified  teeth,  cut  them  into  slices,  completely 
removed  the  acid  by  which  the  decalcification  was  done,  and 
planted  the  fungus  upon  these  as  culture  media.  He  found  that 
they  make  a  good  growth  without  other  nutrient  material. 


72  PATHOLOGY    OF    THE    HABD    TISSUES    OF    THE   TEETH. 

Within  my  personal  observation,  caries  of  dentin  has  seemed 
to  progress  most  rapidly  when  closely  shut  in  by  overlapping 
enamel,  and  less  rapidly  when  the  opening  to  the  fluids  of  the 
mouth  was  broad  and  ample.  Finally,  when  the  carious  area 
is  so  flat  as  to  be  kept  clean  by  mastication  and  is  fully  exposed 
to  washings  by  the  saliva,  the  decay  ceases.  The  fungus  is 
facultative  anaerobic,  growing  ordinarily  in  the  presence  of 
oxygen,  but  having  the  faculty  of  growing  quite  as  well  in  the 
absence  of  oxygen.  It  grows  well  in  culture  media  when  all 
oxygen  is  removed,  and  therefore  grows  as  well  when  shut  up  in 
a  deep  cavity.  In  case  the  opening  of  the  cavity  becomes  very 
broad  while  the  cavity  is  yet  shallow,  the  progress  of  decay 
is  apt  to  be  much  slower.  The  explanation  for  this  ditference 
is  that  when  the  opening  to  the  cavity  is  very  broad,  much  of 
the  acid  formed  by  the  microorganisms  is  washed  away  by  the 
saliva.  This  must  be  considered  a  local  factor.  The  intensity 
of  the  condition  of  susceptibility,  which  will  be  discussed  later, 
must  also  be  reckoned  with  as  a  general  factor  when  considering 
the  rapidity  of  caries. 

The  progress  of  caries  is  limited,  or  even  stopped,  in  a 
number  of  different  ways.  The  crowding  of  meats  into  a  cavity 
and  the  establishment  of  putrefactive  decomposition,  an  occa- 
sional occurrence,  is  apt  to  end  the  progress  of  decay  for  the 
time,  and  leave  the  cavity  with  smooth,  hard,  blackened  walls 
by  the  decomposition  of  all  of  the  organic  matrix  from  which 
the  calcium  salts  have  been  removed.  Decay  may  rebegin  in 
this  if  conditions  are  so  changed  as  to  favor  it. 

When  most  of  the  crown  of  a  tooth  breaks  away,  the  prog- 
ress of  caries  will  necessarily  be  across  the  length  of  the  dentinal 
tubules,  because  these  become  horizontal  on  a  level  with  the  pulp 
of  the  tooth.  If  the  organisms  are  prevented  from  entering  the 
tubules  from  the  pulp  canals,  the  progress  of  decay  will  be  very 
slow,  or  there  will  be  no  progress  at  all. 

Wlien  the  pulp  of  the  tooth  has  died  and  alveolar  abscess 
in  the  chronic  form  is  established  with  a  free  discharge  through 
the  root  canals,  the  progress  of  decay  is  generally  stopped  as 
long  as  this  condition  continues.  If,  however,  the  apical  portion 
of  the  root  canal  is  choked  by  debris  or  otherwise  closed,  decay 
may  proceed  from  the  root  canal,  penetrate  the  tubules  and 
rapidly  hollow  out  the  root  to  a  conical  shell  and  destroy  it. 

The  breaking  away  of  the  lingual  or  buccal  wall  of  proximal 
cavities  is  often  a  factor  in  saving  a  tooth  from  destruction, 
especially  among  those  people  who  live  much  on  coarse  food. 


CARIES   OF   DENTIN.  73 

This  has  been  found  in  the  examination  of  some  of  the  older 
Indian  remains,  especially  of  those  tribes  that  were  supposed 
to  eat  much  parched  corn.  The  food  forced  through  the  cavity 
in  mastication  and  out  through  the  broken  side  kept  the  surface 
worn  smooth.  The  opportunity  to  know  and  to  watch  this  among 
our  own  people  occurs  frequently. 

The  question  as  to  whether  caries  is  produced  by  a  single 
species  of  microorganism  or  whether  a  number  of  kinds  are 
acting  together  is  often  asked.  As  to  this,  there  are  several 
organisms  found  in  the  saliva  of  practically  every  person  that 
have  physiological  characters  which  seem  to  fit  them  for  the 
production  of  caries,  and  no  reason  is  known  why  they  may  not 
be  acting  together  in  the  same  carious  cavity.  Dr.  Miller  seems 
to  have  found  them  so.  In  the  deepest  portion  of  the  carious 
area  I  have  usually  found  but  a  single  variety,  the  streptococcus. 
In  the  decaying  mass,  however,  pretty  much  all  of  the  varieties 
found  growing  in  the  mouth  may  be  found  and  some  of  them 
penetrate  deeply  into  the  softened  portion.  Especially  a  white 
staphylococcus  is  often  found  deep  in  the  dentinal  tubules,  if 
judged  of  by  the  difficulty  of  keeping  clear  of  it  in  the  effort  to 
get  a  pure  culture  of  the  streptococcus  from  carious  dentin. 

Note. —  I  have  often  spoken  of  this  staphylococcus  as  the  zigzag  coccus,  because 
of  its  habit  of  forming  zigzags  in  its  growth  in  broth.  One  coccus  of  a  pair  divides 
on  the  opposite  pole  from  that  upon  which  the  pair  has  divided,  making  a  square 
turn  instead  of  a  straight  or  curved  line,  as  is  the  more  usual  habit  of  the  strepto- 
cocci. This  organism  dissolves  gelatin  freely  in  artificial  culture.  It  is  frequently 
found  in  suppurating  pulps  and  in  alveolar  abscess,  yet  it  will  generally  fail  to  pro- 
duce pus  when  animals  are  infected  with  it.  It  is  probably  the  white  staphylococcus 
pyogenes  modified  by  continuous  residence  in  the  saliva.  The  streptococcus  spoken 
of  above  I  have  often  called  ' '  caries  fungus, "  or  "  streptococcus  media, ' '  the  latter 
because  of  finding  larger  and  smaller  varieties  occasionally  in  the  saliva.  These  are 
hardly  found  so  continuously  as  to  make  the  latter  term  a  good  one. 


74  PATHOLOGY   OF   THE   HABD   TISSUES   OF   THE   TEETH. 


CAEIES  OF  ENAMEL. 

ILLUSTRATIONS:    FIGURES  V6-98. 

Caeies  of  enamel  differs  from  caries  of  dentin  in  several 
important  jjarticulars.  (1.)  In  caries  of  enamel,  the  microorgan- 
isms are  attached  to  or  lie  upon  the  outside  of  the  enamel.  They 
grow  and  form  the  acid  which  causes  caries  of  enamel  in  that 
position.  They  never  enter  the  tissue  until  the  enamel  rods  are 
loosened  and  fall  out.  The  enamel  is  a  solid  into  which  micro- 
organisms can  not  penetrate.  (2.)  The  enamel  rods  are  cemented 
together  by  a  cementing  substance  which  dissolves  more  readily 
in  an  acid  than  the  rods  themselves,  and  the  first  effect  upon  the 
enamel  is  to  dissolve  out  this  cementing  substance.  The  general 
rule  is  that  in  decays  occurring  on  the  smooth  surfaces  of  the 
teeth,  this  cementing  substance  is  dissolved  through  the  entire 
thickness  of  the  enamel  before  any  enamel  rods  fall  away.  In 
some  of  the  decays  occurring  in  pits,  the  enamel  rods  themselves 
will  be  dissolved,  enlarging  the  pit.  (3.)  The  decaying  spot  upon 
the  enamel  is  always  whitened,  as  the  first  observable  change. 
This  change  in  color  is  sometimes  not  considerable  and  is  very 
easily  overlooked  while  the  teeth  are  wet,  but,  when  the  teeth 
are  dried  and  examined  carefully,  the  color  will  be  found  to  be  a 
grayish  white,  or  even  very  white  in  some  cases,  and  the  out- 
lines are  often  very  clearly  marked.  (4.)  In  such  spots  an 
explorer  is  likely  to  catch  if  passed  lightly  over  the  surface, 
instead  of  gliding  smoothly  as  it  will  on  sound  enamel.  (5.)  For 
these  decays  to  occur,  it  seems  to  be  necessary  that  microorgan- 
isms become  attached  to  the  surface  of  the  tooth,  grow  there  in 
the  form  of  a  colony,  or  in  a  zooglea  formation,  attached  together 
in  a  gelatinoid  matrix,  or  equivalent  covering,  and  produce  fer- 
mentative decomposition  with  acid  formation  at  the  spot,  apply- 
ing the  acid  directly  to  the  solution  of  the  tooth.  (6.)  For  this 
reason,  the  beginning  of  caries  of  the  teeth  occurs  at  such  points 
as  will  favor  such  lodgment  or  attachment  in  which  the  micro- 
organisms will  not  be  subject  to  such  frequent  dislodgment  as 
would  prevent  a  fairly  continuous  growth.  This  is  the  cause  of 
the  localization  of  the  beginnings  of  caries  on  particular  parts 
of  the  surface  of  the  tooth.  It  had  previously  been  supposed 
that  caries  of  the  enamel  might  be  caused  by  acids  dissolved  in 
the  saliva,  or  introduced  with  foods  from  the  outside.     This 


CAEIES   OF   ENAMEL.  75 

idea,  however,  is  no  longer  tenable.  If  caries  of  the  enamel  was 
caused  by  acids  dissolved  in  the  general  saliva,  we  would  not 
have  that  strict  localization  of  decay  that  is  found  in  the  mouth. 
This  localization  is  very  important  and  should  be  very  carefully 
considered. 

The  points  of  localization  abe:  (1.)  Pits  or  fissures  in 
the  occlusal  surfaces  of  the  bicuspids  and  molars,  in  the  buccal 
surfaces  of  the  molars,  and  sometimes  in  the  lingual  surfaces 
also,  and  occasionally  in  the  lingual  surfaces  of  the  upper  incis- 
ors; (2)  In  the  proximal  surfaces  of  all  of  the  teeth;  (3)  In  the 
gingival  third  of  the  buccal  or  labial  surfaces  of  all  of  the  teeth, 
and  rarely  in  the  lingual  surfaces  also.  Ninety-eight  per  cent 
of  all  of  the  decays  that  occur  in  the  human  teeth  are  located 
at  the  points  included  in  this  mention.  Those  beginnings  of 
decay  located  elsewhere  in  the  teeth  are  usually  the  result  of 
accidental  conditions,  proving  the  accuracy  of  the  rule;  (4)  The 
most  prominent  tendency  to  wide  spreading  of  decay  on  the  sur- 
face of  the  enamel  is  a  direction  that,  when  complete,  encircles 
the  tooth  following  close  to  the  free  margin  of  the  gum.  Hence 
proximal  decays  and  gingival  third  decays  spread  most  in  these 
directions.  The  tendency  in  cases  of  unusual  severity  is  for  proxi- 
mal and  buccal,  and  even  lingual  decays,  to  imite  across  the 
angles  of  the  teeth,  making  a  complete  circle  around  the  tooth 
near  the  free  border  of  the  gum. 

It  may  be  laid  down  as  a  principle  that  for  caries  to  begin 
in  the  enamel  of  the  teeth  anywhere,  the  caries  fungus,  which 
forms  an  acid,  must  he  attached  to  the  surface  of  the  enamel  in 
some  such  way  as  to  prevent  the  acid  which  it  forms  from  being 
readily  washed  aivay  and  dissipated  in  the  general  fluids  of  the 
mouth.  Under  all  the  observations  of  the  surroundings  of  the 
occurrence  of  decay  of  the  enamel,  I  fail  to  be  able  to  form  a 
conception  of  its  beginning  without  the  existence  of  some  such 
conditions.  But  it  is  not  insisted  here  that  this  must  always 
be  by  the  formation  of  zooglea  or  gelatinoid  plaques.  This  may 
be  produced  in  an  artificial  way  by  cementing  a  band  on  a  tooth, 
as  is  done  in  orthodontia  operations,  and  omitting  the  cement 
in  a  part  of  the  area  covered.  If  such  a  band  remains  long  on 
the  tooth,  caries  of  the  enamel  will  occur,  even  when  the  patient 
is  otherwise  immime  to  caries.  This  has  been  a  matter  of  care- 
ful experiment  by  the  author.  It  has  also  been  observed  in  many 
orthodontia  cases.  Indeed,  the  amount  of  injury  being  done  in 
this  way  during  the  treatment  of  irregularities,  is  giving  rise 
to  much  complaint. 


76  PATHOLOGY   OF   THE   HAED   TISSUES   OF   THE   TEETH. 

Peneteation  OF  Enamel  in  Pits. 

ILLUSTRATIONS:    FIGURES  75,  76,  77. 

The  beginning  of  caries  in  pits  in  the  occlusal  surfaces  of 
three  molar  teeth  is  shown  in  Figures  75,  76,  77.  It  is  not  diffi- 
cult to  conceive  of  a  colony  of  the  microorganisms  present  in 
the  mouth,  establishing  itself  within  one  of  these  pits  and  grow- 
ing there,  producing  acid  sufficient  to  begin  the  solution  of  the 
cementing  substance  between  the  enamel  rods.  These  would 
be  covered  with  debris  from  foods  that  is  forced  in  upon  them, 
very  completely  shielding  the  acid  formed  from  being  washed 
away  by  the  saliva.  It  seems  to  be  true  that  there  is  a  greater 
intensity  of  the  action  of  the  acid  in  caries  of  enamel  in  this 
position  than  in  any  other,  for  elsewhere  it  is  very  rare  to  see 
the  carious  process  extending  across  the  length  of  enamel  rods, 
or  a  complete  solution  of  any  of  the  rods  before  they  are  loosened 
from  the  dentin.  Caries  usually  follows  accurately  the  length 
of  the  enamel  rods  in  the  penetration  of  the  enamel  in  all  axial 
surface  positions.  But  in  beginning  decays  in  pits,  we  occasion- 
ally see  progress  across  the  length  of  the  enamel  rods,  and  in 
Figure  77  particularly,  less  distinctly  in  Figure  76,  we  may  note 
that  the  pit  has  been  enlarged  at  its  deeper  part  by  the  solution 
of  the  enamel  rods  about  its  walls.  This  kind  of  showing  occur- 
ring frequently,  indicates  that  the  locality  is  more  completely 
isolated,  or  less  disturbed  by  solution  of  the  acid  in  the  oral 
secretions  than  elsewhere,  and  therefore  reaches  the  highest 
percentage  of  acidulation.  It  seems  to  be  for  this  reason  that 
in  this  position  the  rods  themselves  are  often  dissolved  even 
before  the  carious  process  has  extended  into  the  dentin.  The 
spreading  across  the  enamel  rods  is,  however,  often  more  appar- 
ent than  real,  for  about  pits  the  enamel  rods  are  all  inclined 
toward  the  pits.  It  will  be  noted  also,  in  the  examination  of 
these  illustrations,  that  there  is  no  sign  of  the  carious  process 
on  the  surface  of  the  enamel  outside  the  pit.  It  is  confined 
exclusively  to  the  walls  of  the  pits  and  usually  to  the  deeper 
part.  Occasionally  pits  that  are  gradually  narrowed  from  sur- 
faces much  inclined,  or  in  a  fimnel  shape,  will  show  caries  extend- 
ing a  little  out  of  the  pit  proper,  but  this  is  unusual.  This  absence 
of  superficial  extension  is  because  the  surfaces  immediately 
about  the  pits  are  kept  clean,  or  reasonably  clean,  in  the  process 
of  mastication;  and  further,  because,  if  microorganisms  were 
growing  in  such  a  position,  they  would  be  subjected  to  continual 


Fia.  75. 


? 


Fig.   76. 


Figs.  75,  70,  TV.     I'liutograplis  from  split  tcelli    slmwin;;   jiit    dfcays  of   occlusal   surfaces.      Sec 
liclow    Fi^uie    7  7    for   descriptions   of   these   illustrations. 

9b 


Fig.  77. 


Figs.  75,  76,  77.  Photographs  from  split  teeth  showing"  progressively  the  beginning  and  progress 
of  decay  of  the  enamel  in  pits  in  the  occhisal  surfaces  of  molar  teeth.  Each  illustration  is  from  a 
different  tooth.  Figure  75  represents  ahnost  the  earliest  beginning  of  caries  in  the  pit,  showTi  by  the 
whitening  of  the  enamel  of  the  walls  of  the  pit,  that  can  be  distinctly  recognized  in  a  photograph. 
Figure  7G  is  a  more  distinctive  showing  of  decay  made  by  the  deeper  whitening  of  the  enamel  about  the 
pit  and  the  aiipearancc  of  slight  solution  of  its  walls.  In  Figure  77  more  decided  advance  has  been 
made  in  the  whitening  of  the  enamel  and  loss  of  substance  in  the  walls  of  the  pit.  The  acid  has.  in 
this  case,  passed  tlie  dento-enaniel  junction  and  an  effect  in  the  dentin  is  seen.  In  this  tooth  there  is 
also  a  smooth  surface  decay  of  the  enamel  beginning  in  the  mesial  surface,  which  has  also  been  cut 
through  centrally.  This  shows  as  a  faintly  whitened  area,  broad  on  th?  surface  and  penetrating  deepest 
in  its  central  part.  Its  form  is  characteristic  of  smooth  surface  beginnings  of  decay  of  the  en;imel.  and 
is  placed  here  in  sharp  contrast  with  the  forms  of  beginning  decay  of  enamel  in  pits. 


Fia.   78. 


Fig.  78.  Caries  of  enamel.  A  white  carious  spot  on  the  distal  surface  of  a  central  incisor.  It 
has  very  sharp  and  definite  outlines,  though  not  very  regnlar. 

Fig.  79.  An  incisor  removed  for  a  girl  nine  years  of  age.  split  through  areas  of  decay  and  show- 
ing the  broad  pulp  chamber  of  that  age.  A  decay  in  the  mesial  surface  had  destroyed  the  pulp.  In 
the  distal  surface  there  is  an  area  of  decay  in  the  enamel,  which,  superficially,  was  similar  to  the  one 
shown  in  Figure  78,  but  not  so  white.  This  is  very  typical  of  the  fonn  of  these  smooth  surface  decays 
of  enamel  in  its  conical  shape,  with  the  broad  base  of  the  cone  on  the  surface  of  the  enamel  and  the 
apex  of  the  cone  toward  the  dento-enamel  junction.  In  this  case  the  apex  of  the  cone  has  just  pene- 
trated the  enamel.  A  little  solution  of  the  lime  salts  of  the  dentin  has  begim  by  the  percolation  of 
acid  from  the  surface  through  the  thickness  of  tlie  enamel.  No  enamel  rods  have  fallen  away  and  no 
microorganisms  have  been  admitted.  Notice  that  a  delicate  hyaline  zone  fringed  with  shade  streaks 
away  toward  the  pulp,  following  the  direction  of  the  dentinal  tubules. 


Fig.   81. 


Fig.  so.  a  split  lateral  incisor,  with  a  very  white  decay  of  enamel  in  its  distal  surface,  showing 
a  modification  of  the  conical  form  of  penetration.  This  has  just  penetrated  the  enamel,  and  the  hya- 
line area,  which  may  already  be  traced  to  the  pulp  chamber,  is  unusually  dark  for  such  a  case.  These 
areas  of  effect  in  the  dentin  beyond  the  area  of  actual  decay  vary  greatly  in  light  and  shade.  Pho- 
tographs of  these  areas  vary  greatly,  because  of  differences  in  the  translucency  of  different  teeth.  A 
tooth  that  has  become  very  dry,  becomes  opaque  and  often  fails  to  show  these  shadows,  or  shows  them 
differently. 

Fig.  81.  A  very  narrow  area  of  decay  penetrating  the  enamel  in  the  distal  surface  of  a  cuspid. 
In  this  the  action  of  acid  has  been  confined  to  a  very  narrow  area  of  the  surface  of  the  enamel.  The 
decay  has  reached  the  dentin,  following  accurately  the  length  of  the  enamel  rods.  The  enamel  rods 
have  fallen  out  of  its  central  portion,  microorganisms  have  been  admitted  and  decay  of  the  dentin  has 
begun.  Other  parts  of  the  photogi'aph  are  indistinct  because  it  was  made  when  the  tooth  was  dry  and 
the  surface  opaque.  For  the  same  reason  the  hyaline  area  streaking  inward  toward  the  pulp  does  not 
show.     Some  translucence  is  necessary  to  show  these  by  photography. 


Fig.  82.  A  photoinicrognipli  showing  nn  awn  uf  ck'cay  in  llio  enamel  in  the  distal  surface  of_  an 
incisor.  The  incisal  edge  of  the  tooth  is  upward.  All  the  illustrations  from  perpendicular  sections 
have  been  so  placed.  The  letter  d  is  placed  on  the  dentin,  e.  is  on  the  enamel.  The  dento-enaniel 
junction  is  between  these  two  letters.  x.  The  beginning  point  of  the  decay  of  the  enamel.  z.  An 
e.xtension  of  the  superficial  decay  toward  the  incisal.  The  irregularity  of  the  line  of  deepest  penetra- 
tion is  common,  as  seen  in  photomicrographs.  In  this  figure  the  enamel  rods  in  the  decayed  area  have 
been  disturbed  in  mounting,  distorting  the  edge  reijrcsenting  the  surface  of  the  tooth.  Areas  of  decay 
which  show  white  by  reflected  light  are  opaque  and  show  daik  by  transmitted  light. 


Fin.   83.   A  photomicrogrnph  of  a.  small  area,  of  llic  beginning  of  carips  in   pnamol  that  shows  an 
unusually  smooth  rounding  of  the  deep  line  of  penetration.         D.   Dentin.  e.   Enamel.     The  dento- 

enamel  junction   is  between   these  two  letters.  x.      A  distinct  swelling  of   the  decayed   area.     This 

swelling  is  common  in  areas  of  decay  in  enamel. 


Fig.  S4.     Caries  of  enamel.  d.   Dentin.  e.  Enamel.         X.  Area  of  decay.     In  this  figure  the 

oviter  ends  of  the  enamel  rods  have  been  broken  away  in  grinding-.  Notice  particularly  the  flamelike 
tongues  of  penetration  sweeping  toward  the  dento-cnatnel  junction,  following  the  lines  of  the  length  of 
the  enamel  rods.  Also  the  penetration  on  the  margins  of  the  principal  area  are  seen  to  follow  the 
lines  of  the  length  of  the  enamel  rods.  This  rigid  following  of  the  enamel  rods  is  a  characteristic  of 
caries  of  enamel  beginning  in  smooth  surfaces. 


Fig.  Sfj. 


Fig.   85.     A  broader  and  flatter  area  of  carious  enamel.  d.   Dentin.  e.   Enamel.         X.    Area 

of  decay.  Here  also  we  find  the  same  inclination  to  the  formation  of  flamelike  tongues  sweeping 
toward  the  dento-enamel  junction,  following  the  length  of  the  enamel  rods.  There  is  no  spreading  of 
decay  across  the  length  of  the  enamel  rods.  All  spreading  is  in  new  beginnings  to  the  side  on  the 
surface  of  the  enamel. 


CAKIES   OF   ENAMEL.  77 

washings  by  the  saliva,  which  would  dissipate  the  acid  formed. 
Therefore,  decays  of  the  enamel,  beginning  in  pits,  are  in  the 
form  of  a  cone,  having  the  base  on  or  toward  the  dento-enamei 
junction,  and  the  apex  toward  the  surface. 

Penetration  of  Enamel,  in  Proximal  Surfaces  of  Incisors. 

ILLUSTRATIONS:    FIGURES  78-85. 

The  conditions  are  entirely  different  on  the  smooth  surfaces 
of  the  teeth,  as  the  proximal  surfaces.  Here  there  is  no  pit  or 
fissure,  depression  or  fault  in  the  enamel.  It  is  a  smooth,  rounded 
surface.  The  teeth  round  together  normally  in  such  a  way  that 
the  interproximal  gum  tissue  fills  the  space  to  the  contact  point, 
and  the  contact  point  proper  is  fairly  well  rounded  in  most  cases. 
While  this  condition  continues  perfect,  there  is  no  place  for  the 
lodgment  of  microorganisms  upon  the  proximal  surfaces,  but, 
whenever  the  gum  tissue  fails  to  fill  this  space  completely  and  a 
little  opening  is  left  to  the  gingival  of  the  contact  point,  it  forms 
a  harbor  or  nidus  at  which  microorganisms  may  lodge  and  begin 
their  growth.  It  is  probable  that  by  this  growth  alone  they  may 
have  something  to  do  with  forcing  the  gum  tissue  a  little  bit 
further  away,  and,  if  they  are  sufficiently  protected  from  wash- 
ings by  the  saliva,  they  may  form  sufficient  acid  to  produce  an 
action  upon  the  calcium  salts  of  which  the  enamel  is  formed. 

Figures  78-81  are  a  group  showing  the  manner  of  the  pene- 
tration of  enamel  by  caries  in  the  proximal  surfaces,  as  may  be 
well  seen  in  split  teeth  with  an  ordinary  hand  magnifier.  Fig- 
ures 82-84  illustrate  the  same  thing  in  photomicrographs*  pro- 
duced by  low  powers  of  the  microscope.  The  first  beginning  of 
decays  upon  these  surfaces  is  often  small,  as  is  shown  by  Figure 
78,  a  photograph  of  the  distal  surface  of  a  central  incisor  with 
the  spot  of  beginning  decay  very  exactly  in  the  position  men- 
tioned, just  to  the  gingival  of  the  contact  point.  This  was  a  very 
white  spot  on  a  tooth  that  was  rather  dark  in  its  general  color, 
so  that  the  engraver  has  been  able  to  show  it  very  distinctly.  We 
might  ask  here,  by  what  power,  circumstance  or  condition  has  the 
action  of  the  acid  been  confined  to  this  one  small  spot,  while  all 
the  rest  of  the  surface  of  the  tooth  is  free  from  any  action  of 
the  acid? 


*  The  difference  between  the  photograph  and  the  photomicrograph,  constantly 
observed  in  their  use  in  this  work,  is  that  the  photograph  is  taken  from  an  opaquo 
object  by  reflected  light,  while  the  photomicrograph  is  taken  from  a  thin  section  by 
transmitted  light.    Usually  the  object  is  much  less  enlarged  in  the  photograph. 


78  PATHOLOGY    OF    THE    HAKD    TISSUES   OF   THE    TEETH. 

Figure  79  is  a  photograph  from  a  central  incisor  that  has 
been  split  mesio-distally  through  a  white  spot  upon  its  distal 
surface  but  little  larger  that  the  one  shown  in  Figure  78.  In  this 
we  see  the  penetration  into  the  enamel  in  the  form  of  a  some- 
what flattened  cone,  or  a  cone  with  a  broad  base  on  the  surface 
of  the  enamel,  and  the  point  just  reaching  through  to  the  dento- 
enamel  junction.  As  we  will  see  quite  distinctly  later,  in  caries 
of  the  enamel  more  highly  magnified,  the  solution  of  the  cement- 
ing substance  between  the  enamel  rods  follows  directly  the  length 
of  the  enamel  rods  and  continues  spreading  upon  the  surface 
from  a  spot  of  much  smaller  beginning  than  that  now  seen.  At 
the  central  beginning  point,  or  nidus,  the  effect  of  the  acid  has 
reached  through  the  enamel  to  the  dentin  and  is  beginning  to 
dissolve  it,  while  the  depth  of  penetration  is  less  and  less  about 
that  central  point  in  every  direction,  until  it  runs  out  to  quite 
a  thin  edge  at  the  surface  of  the  enamel.  This  is  characteristic 
of  beginning  decays  in  enamel  upon  all  of  the  smooth  surfaces 
of  the  teeth.  They  begin  at  a  central  nidus,  or  beginning  point, 
and  spread  sometimes  in  every  direction,  but  generally  spread 
most  in  some  particular  direction  from  that  beginning  point, 
as  will  be  described  later.  Not  infrequently  decay  begins  at 
several  points  close  together  in  a  more  or  less  even  row,  which 
takes  some  particular  direction. 

In  Figure  80  we  have  another  illustration  similar  to  that 
in  Figure  79,  also  a  photograph  from  a  lateral  incisor,  cut  mesio- 
distally,  with  a  cavity  in  the  distal  surface.  This  was  a  very 
white  decay  and  shows  to  advantage.  It  will  be  seen  that  there 
has  been  considerable  spreading  both  ways  from  the  central 
nidus,  and  that  the  central  portion  has  just  penetrated  to  the 
dento-enamel  junction  and  is  quite  a  little  in  advance  of  the 
general  conical  form  of  the  invasion  of  the  enamel.  Decays 
occur,  however,  that  show  very  little  or  none  of  this  spreading 
upon  the  surface,  even  upon  the  proximal  surfaces  of  the  teeth, 
as  will  be  seen  from  an  examination  of  Figure  81.  The  tooth  is 
a  little  more  enlarged  in  order  to  show  this  spot  to  better  advan- 
tage. Here  it  will  be  seen  that  a  cavity  has  formed  in  the  enamel. 
Some  of  the  enamel  rods  have  fallen  out  and  the  effect  of  the 
acid  has  passed  entirely  through  the  enamel  and  begun  to  dis- 
solve the  calcium  salts  from  the  dentin,  and  yet  the  opening, 
or  the  area,  of  the  enamel  affected,  as  seen  in  this  dimension 
(the  tooth  having  been  cut  mesio-distally  from  occlusal  to  gingi- 
val), is  no  larger  than  the  shaft  of  a  large  pin.  The  enamel  rods 
have  been  exactly  followed  lengthwise,  and  the  enamel  about 


CABIES   OF   ENAMEL.  79 

it  seems  free  from  the  action  of  acid.  Again  it  might  be  asked : 
By  what  power,  circumstance  or  condition  has  the  action  of  the 
acid  been  confined  to  this  narrow  area? 

This  following  of  the  enamel  rods  is  better  seen  in  photo- 
micrographs, in  which  the  enlargement  is  only  just  sufficient 
for  the  direction  of  the  enamel  rods  to  be  made  out.  If  a  very 
high  power  is  used,  a  sufficient  area  of  the  tissue  of  the  tooth 
can  not  be  included  in  the  pictiire  to  give  a  correct  idea  of  the 
general  form  and  relation  of  the  different  parts.  It  must  be 
understood  that  a  decayed  area  that  is  white  to  reflected  light, 
shows  an  opacity  to  transmitted  light  and  is  dark  in  the  photo- 
micrograph unless  it  is  groimd  excessively  thin.  This  group 
of  sections.  Figures  82,  83,  84,  85,  are  all  cut  from  occlusal  to 
gingival.  Beginning  decays  of  the  enamel  cut  in  this  direction 
show  but  little  superficial  spreading  as  compared  with  that  seen 
in  cross  section,  which  will  be  given  later.  The  characters  as 
to  penetration,  however,  are  the  same,  only  less  extended 
laterally. 

Figure  82  is  a  photomicrograph  from  a  lateral  incisor  with 
a  beginning  decay  of  the  enamel  that  was  very  similar  to  that 
shown  in  the  photograph.  Figure  80.  The  form  of  the  penetration 
and  of  the  spreading  on  the  surface  are  quite  remarkably  alike 
in  the  two  cases.  There  has  been  a  little  disturbance  of  the 
injured  tissue  by  crushing  it  together  just  above  x  forming  the 
notch  midway  between  x  and  z.  There  has  also  been  some  loss 
of  the  outer  ends  of  the  enamel  rods  from  this  notch  to  the  letter 
z,  but  the  main  feature  of  the  illustration,  the  line  of  penetra- 
tion, is  in  perfect  form.  The  starting  point  of  the  decay  was 
about  the  position  of  the  letter  x,  and  it  has  spread  superficially 
in  both  directions.  In  this  case,  the  spreading  has  been  most 
toward  the  incisal  angle,  as  was  the  case  in  the  photograph.  Fig- 
ure 80.  The  tendency  of  the  line  of  invasion  to  be  broken  up 
into  flamelike  tongues  shooting  forward  of  the  general  line  may 
also  be  noted. 

Figure  83,  a  photomicrograph  from  a  proximal  decay,  is 
almost  unique  in  the  smooth  roundness  of  its  deeper  portion. 
It  shows  almost  none  of  the  flamelike  tongues  shooting  toward 
the  dento-enamel  junction  that  are  common  characteristics  of 
the  deep  border  of  advancing  caries  of  enamel.  The  accretion 
lines  of  Retzius  are  brought  out  much  more  clearly  in  the  decayed 
area.  This  is  quite  general  when  the  direction  of  the  section 
is  squarely  across  them.  In  many  instances,  however,  this  seems 
not  to  occur.    The  swelling  of  the  decayed  area  is  well  seen  at  x. 


80  PATHOLOGY    OP    THE    HAED    TISSUES    OF    THE    TEETH. 

This  is  constantly  seen  in  decays  at  this  stage  when  no  enamel 
rods  have  been  lost  during  the  preparatory  work. 

Figure  84  is  a  photomicrograph  from  a  proximal  decay  of 
the  enamel  at  x,  which  is  very  narrow  on  the  surface  and  pene- 
trates almost  to  the  dento-enamel  junction  at  the  point  of  the 
cone.  This  cone  is  of  somewhat  irregular  outline.  In  this  case 
the  outer  ends  of  the  enamel  rods  were  lost  in  grinding.  Notice 
particularly  that  at  different  points  the  tendency  is  for  decay 
to  advance  in  little  flamelike  tongues  or  projections,  each  fol- 
lowing the  length  of  the  enamel  rods.  This  is  a  characteristic 
of  caries  of  enamel,  and  often,  when  examined  in  the  very  early 
beginning,  the  starting  points  are  divided  from  each  other  with 
these  little  flamelike  tongues  projecting  inward  toward  the 
dento-enamel  junction.  This  is  seen  also  in  Figure  85  in  a  decay 
at  X,  which  is  much  broader  and  flatter,  showing  less  of  the  coni- 
cal form.  In  this,  a  nidus,  or  beginning  point,  upon  the  sur- 
face of  the  enamel  has  been  just  above  the  letter  x,  and  it  has 
spread  quickly  over  the  surface  to  the  gingival  and  the  occlusal 
of  this  point  by  the  increase  in  size  of  the  growing  colony  of 
microorganisms  on  the  surface.  Each  new  beginning,  with  indi- 
vidual enamel  rods,  or  groups  of  rods,  follows  exactly  along 
its  length  toward  the  dento-enamel  junction.  Other  illustra- 
tions will  show  this  tendency  more  prominently  than  these  two. 

In  examining  many  photomicrographs  of  caries  of  the 
enamel,  we  find  this  tendency  constant  and  the  following  of  the 
length  of  the  enamel  rods  very  rigid.  We  never  find  caries  of 
the  enamel  spreading  laterally  in  the  interior  of  this  tissue.  It 
always  goes  straight  from  its  starting  point  to  the  dento-enamel 
junction  and  then  spreads  out  in  the  dentin.  In  order  for  decay 
to  spread  out,  involving  a  larger  area  of  enamel  laterally  in  any 
direction,  the  spreading  must  be  in  the  form  of  new  beginnings 
on  the  surface.  In  other  words,  all  spreading  of  decay  of  enamel 
from  the  beginning  point  is  brought  about  by  conditions  which 
allow  of  growth  and  spreading  of  colonies  of  microorganisms 
on  the  surface  of  the  tooth.  No  matter  how  broad  the  carious 
area,  it  projects  inward  in  these  little  flamelike  tongues  along 
its  deeper  border.  Therefore,  decays  of  the  enamel,  beginning 
in  smooth  surfaces,  are  generally  in  the  form  of  a  cone,  having 
the  base  at  the  surface  of  the  enamel,  and  the  apex  toward  the 
dentin. 


Fid.    8G. 


Fia.  87. 


Fig.   88. 


Fia.   80. 


FiQS.  86,  87,  88,  89.  Photographs  from  four  bicuspid  teeth  with  superficial  proximal  decays.  To 
show  distinctly  the  gingival  line,  the  first  two  have  been  stained  slightly  with  eosin,  which  does  not 
stain  the  enamel.  The  four  teeth  have  been  arranged  to  show  progressively  the  disposition  of  caries  to 
spread  bucco-lingually  on  the  proximal  surfaces  of  these  and  the  molar  teeth.  While  decay  is  apt  to 
begin  first  just  to  the  gingival  of  the  contact  point  and  is  confined  between  that  and  the  free  border  of 
the  gum  occluso-gingivally,  it  is  free  to  spread  bucco-lingually  as  far  as  the  sweep  of  food  through  the 
embrasures,  formed  by  the  rounding  of  the  angles  of  the  teeth  away  from  each  other,  will  allow.  In 
Figure  86  the  aiea  bucco-lingually  is  very  narrow.  In  Figure  87  a  little  broader,  and  in  Figure  88  it 
reaches  fully  to  the  embrasures.  In  Figure  89  something  of  the  disposition  of  decay  to  begin  at 
numbers  of  small  points  along  this  bucco-lingual  line,  is  seen. 

10 


Flu.  90.  A  bicuspid  in  which  there  is  seen  a  disposition  to  broader  spreading  occhiso-gingxvally. 
Sometimes  this  is  very  extpiisive,  as  will  be  illustrated  later. 

Fig.  91.  An  upper  niolnr  in  which  is  seen  the  same  disposition  to  spread  bucco-lingiially  as  occurs 
in  the  bicuspids.  This  form  of  spreading  is  common  to  the  bicuspids  and  molars.  In  this  case  the 
enamel  rods  have  fallen  out  of  a  small  area  at  the  point  of  first  beginning. 

10a 


Fia.  U2. 


Fig.  93. 


Fig.  92.  A  cross  cut  of  a  bicuspid  crown  showing'  decay  on  both  the  mesial  and  distal  surfacea. 
This  has  the  advantage  of  showing  the  spreading  of  the  decay  bucco-lingually  in  its  relations  to  the 
angles  of  the  teeth.  On  the  right  side  of  the  picture  the  spreading  of  decay  is  from  angle  to  angle; 
indeed,  somewhat  around  the  curve  on  the  lingual.  Also  the  decay  is  seen  to  have  begun  at  several 
points  along  the  line  from  buccal  to  lingual.  Some  solution  of  the  calcium  salts  of  the  dentin  is  in 
progress,  though  no  enamel  rods  have  fallen  away  and  microorganisms  have  not  been  admitted.  A 
broad  area  of  decay  is  shown  in  such  an  illustration,  because  the  cut  is  along  the  length  of  greatest 
spreading  on  the  surface.  A  section  lengthwise  of  the  tooth  would  show  a  narrow  area  of  decay.  On 
the  left  margin  of  the  illustration,  the  area  of  decay  is  not  central  because  the  first  bicuspid  was  in 
lingual  occlusion.     Hence  the  anomalous  position  of  the  beginning  of  decay. 

Fig.  93.  A  cross  cut  of  the  crown  of  a  bicuspid  with  a  decay  that  has  begim  at  a  number  of 
points,  which  have  penetrated  the  enamel  separately,  leaving  some  areas  of  sound  enamel  between 
them   at  the  time  of  extraction,   but  on   the  surface  all   had  united. 


H 

^^1 

^W^ 

*  ^fl 

^^B 

'  H 

^^\ 

^^1 

^L 

.^^^fl 

^k 

'  f**^^      .^^^^^^^^^^1 

Fio.    94. 


Fig.  94.  An  upper  first  molar  cut  across  the  crown,  showing:  a  solid  area  of  caries  of  the  enamel 
stretching  bucco-Iing^ually  from  angle  to  angle  of  the  distal  surface,  which  has  just  reached  the  dento- 
enamel  junction  at  one  point.  One  should  note  especially  the  thinning  out  to  the  surface  of  the  decay 
of  enamel  rounding  slightly  toward  both  the  buccal  and  lingual  angles,  and  the  amount  of  sound 
enamel  that  would  have  to  be  removed  in  order  to  remove  the  last  of  the  carious  enamel  in  the  prepa- 
ration of  such  a  case  for  tilling. 

Fig.  95.  An  upper  first  molar  with  a  less  extensive  decay  of  the  enamel,  which  has  reached  the 
dentin  at  two  points.  In  this  case  the  beginning  of  the  decay  was  much  further  toward  the  gingival 
line  than  usual,  and  the  enamel  is  very  thin. 


_gfg^tS^ 

^0g 

I^^^Hj 

^^^^^HB^^M^!^,  c!^^^ 

V*-*^                   V  ^<- W.>A\'C  V" .                              '  ji    ^Sh 

^Hr      % 

^A^^^^W^MHBflaM^^^WHBI^^B 

bb^^^^^^^Ik>'^ 

^r 

■*« 

nP-,, 

* 

^^B  * 

^HBl.  .  . 

.    :    .!  ,  ',;                ^ 

Fig.  96.  A  photomicrograph  showing  a  portion  of  a  section  of  enamel  in  which  caries  has  pro- 
gressed part  way  through  its  thickness.  e.  Enamel  that  is  perfect.  X.  Decayed  enamel.  Tlie 
decayed  portion  of  the  enamel  has  been  filled  with  yellow  shellac,  which  has  taken  the  place  of  the 
cementing  substance  dissolved  out  from  between  the  rods,  and  takes  dark.  The  sound  enamel,  being 
solid,  does  not  absorb  the  shellac.  The  plan  of  doing  this  is  given  in  the  text.  In  this  particular 
section  not  much  of  the  structure  of  the  enamel  can  be  seen  in  the  undecayed  portion. 


FiQ.   97. 


FiQ,    9i.     A   photomicrograph   of  enaiiul    in   wliich   caries  has  made   considerable  progress.         d. 
Dentin.  E.    Enamel.         x.    Carious   enamel.      The   dento-enamel   junction  is   seen  between   D   and    E. 

In  this  case,  the  enamel  rods  appear  fairly  well  in  the  sound  enamel  and  a  considerable  irregularity  in 
their  course  may  be  observed.  The  decayed  area  is  filled  with  yellow  shellac.  The  enamel  rods  appear 
smaller  in  the  decayed  area. 


GAMES   OF   ENAMEL.  81 

SuPEBFiciAL  Spreading  of  Caries  in  Proximal  Surfaces 
OF  Bicuspids  and  Molars. 

ILLUSTRATIONS:    FIGURES  86-05. 

We  pass  now  to  the  superficial  conditions  as  seen  in  the 
proximal  surfaces  of  the  bicuspids  and  molars.  If  we  examine 
the  whitened  outlines  seen  upon  the  surfaces  of  the  teeth  before 
any  enamel  rods  have  fallen  away,  we  will  find  these  decays 
taking  certain  definite  forms  by  reason  of  spreading,  and  often 
starting  at  several  points  instead  of  at  one  central  nidus.  A 
knowledge  of  these  forms  and  the  reasons  for  them,  is  of  great 
importance  in  the  treatment  of  caries. 

The  group  of  illustrations,  Figures  86-89,  inclusive,  shows 
the  principal  varieties  of  form  produced  by  the  spreading  bucco- 
lingually  of  beginning  decays  in  the  proximal  surfaces  of  the 
bucuspids  as  seen  in  whole  teeth.  This  tendency  is  practically 
the  same  in  the  molars,  as  seen  in  Figure  91.  These  may  be 
confined  to  a  round  spot,  as  is  often  the  case  in  the  incisors,  as 
shown  in  Figure  78,  but  the  more  general  tendency  is  to  spread 
buccally  and  lingually  from  the  beginning  point.  This  is  shown 
progressively  in  the  different  pictures  of  this  group  and  illus- 
trates the  common  tendency  of  caries  of  the  enamel  to  spread 
in  these  particular  directions.  Occasionally  the  tendency  to 
spread  gingivally  is  seen,  as  is  illustrated  in  Figure  90.  The 
cause  of  this  will  be  more  explicitly  discussed  later.  It  should 
be  noticed  particularly  here  that  the  tendency  is  to  spread  bucco- 
lingually  rather  than  gingivally,  though,  as  will  be  shown 
later,  wide  spreading  gingivally  occurs  under  certain  conditions. 
Spreading  occlusally  does  not  ordinarily  occur,  because  that 
part  of  the  surface  from  the  contact  occlusally  is  cleaned  by 
mastication.  As  we  shall  see  later,  decays  that  begin  much  to 
the  gingival  of  the  contact  point  may  spread  occlusally.  These 
beginning  decays  are  characteristic  of  the  surface  areas  of 
beginning  decays  in  the  proximal  surfaces  in  the  bicuspids  and 
molars.  It  will  be  readily  seen  that  if  the  cut  is  made  horizon- 
tally instead  of  lengthwise  of  the  tooth,  as  in  split  teeth  herein 
before  shown,  the  area  of  decay  presented  would  be  very  dif- 
ferent. 

In  the  group  of  illustrations,  Figures  92-95,  inclusive,  cross 
sections  are  shown  illustrating  the  conditions  from  that  view. 
Here,  instead  of  the  narrow  area  of  decay  seen  in  the  whole 
teeth,  as  in  the  group  86-91,  the  teeth  are  cut  crosswise  through 
similar  areas  of  decay.  These  have  the  additional  value  of  show- 
u 


B2  PATHOLOGY   OF   THE   HAED   TISSUES   OP   THE   TEETH. 

ing  both  tlie  spreading  buccally  and  lingually  and  at  the  same 
time  the  penetration  of  the  enamel  along  this  line  in  its  rela- 
tions to  the  individual  teeth  as  a  whole.  In  three  of  the  four 
figures,  the  decay  has  spread  across  the  proximal  surfaces  to 
the  roiinding  of  the  angle  which  opens  the  embrasures,  both 
to  the  buccal  and  to  the  lingual,  practically  before  decay  of  the 
dentin  has  begun.  Figure  92  is  from  a  mouth  with  thick  necked, 
squarely  built  teeth,  in  which  the  lingual  surfaces  of  the  second 
bicuspids  are  equally  broad  with  the  buccal,  and  with  very  flat 
proximal  surfaces.  On  the  distal,  the  decay  reaches  fully  from 
angle  to  angle.  It  is  easily  seen  in  this  that  there  were  two 
nearly  equal  beginning  points  which  have  run  together  on  the 
surface,  but  are  still  divided  in  the  deeper  part.  On  the  mesial 
surface,  it  is  noted  that  the  original  beginning  was  much  to  the 
lingual  at  the  point  where  whitening  completely  penetrates  the 
enamel  for  a  little  space.  The  spreading  is  toward  the  buccal 
and  toward  the  lingual  from  that  point.  It  spreads  a  little 
around  the  mesio-lingual  angle  but  does  not  reach  the  mesio- 
buccal  angle.  It  is  easy  to  determine  by  this  that  the  position  of 
the  first  bicuspid  was  abnormally  to  the  lingual  of  the  line  of 
the  arch.  This  gave  the  opportimity  for  decay  in  this  unusual 
position.  It  was  prevented  from  reaching  the  mesio-buccal 
angle  by  the  cleaning  of  this  part  by  excursions  of  food  crushed 
along  this  portion  of  the  surface  in  mastication. 

In  Figure  93  there  has  been  an  unusual  number  of  very 
small  beginning  points  forming  a  line  which  had  just  fused 
together  by  the  superficial  spreading.  It  is  particularly  inter- 
esting from  that  fact.  The  tooth  seems  out  of  form  for  the 
reason  that  the  decayed  side  was  cut  farther  from  the  occlusal 
surface  than  the  sound  side.  Figure  94  shows  an  area  of  decay 
on  the  distal  surface  of  a  molar  that  is  of  the  more  regular 
type,  showing  a  solid  advance  of  decay  of  the  enamel,  except 
as  it  thins  out  at  the  angles  of  the  tooth.  This  photograph  gives 
in  relief,  to  speak  figuratively,  the  reason  for  many  cases  of 
recurrence  of  decay  after  filling.  The  cutting  had  been  carried 
to  hard  enamel,  but  not  far  enough  to  remove  the  thin  portion 
of  the  decay  spreading  farther  around  toward  the  angles.  If 
the  filling  were  finished  without  sufficient  separation  of  the  teeth 
having  been  made,  so  that  a  little  of  the  raesio-distal  breadth 
of  the  tooth  was  lost,  the  area  of  near  contact  was  increased 
by  that  much,  giving  better  opportunity  for  decay  to  rebegin. 
Therefore,  the  filling  is  quickly  undermined. 

Many  of  the  beginning  decays  observed  in  the  proximal  sur- 


CABIES   OF    ENAMEL.  83 

faces  are  of  much  less  extent  than  in  these  three  figures.  Indeed, 
the  general  rule  is  that  the  enamel  rods  have  fallen  away  in  the 
central  area  quite  a  little  before  the  spreading  has  reached  its 
bucco-lingual  limit.  In  this  case,  the  spread  of  decay  in  the 
dentin,  along  the  dento-enamel  junction,  backward  decay  of  the 
enamel  and  breaking  away  of  enamel,  so  change  the  conditions 
as  to  stop  the  superficial  beginnings  in  the  enamel.  Figure  95 
sufficiently  illustrates  this.  In  this  case,  the  spreading  bucco- 
lingually  is  not  yet  great,  but  the  decay  has  penetrated  the 
enamel  at  two  minute  points,  and  solution  of  the  calcium  salts 
of  the  dentin  has  begun.  In  a  little  more  time  the  enamel  rods 
would  have  fallen  away  from  all  of  the  central  part  of  the  area 
and  so  changed  the  conditions  that  the  superficial  spreading  of 
caries  would  have  ceased. 

A  Closer  Examination  of  the  Injury  to  the  Enamel. 

ILLUSTRATIONS:    FIGURES  96-98. 

Before  studying  further  the  cause  of  the  localization  and 
tendency  to  the  spreading  of  caries  in  particular  directions  on 
the  surface  of  enamel,  it  may  be  well  to  examine  more  closely 
the  injury  produced.  For  the  illustration  of  this,  the  photo- 
micrographs have  been  taken  from  thin  sections  of  decays  begin- 
ning in  the  enamel  that  were  in  every  way  similar  to  those  shown 
in  other  illustrations,  but  with  an  amplification  that  is  sufficient 
to  display  the  condition  of  the  tissue  without  being  excessively 
magnified.  This  enables  a  larger  area  of  tissue  injured,  in  com- 
parison with  the  uninjured  tissue,  to  be  shown  on  the  ordinary 
book  page  than  seems  practicable  with  a  higher  amplification. 
In  Figures  96,  97,  special  preparation  of  the  tissue  has  been  made 
to  show  the  removal  of  the  cementing  substance  from  between 
the  enamel  rods  by  filling  the  spaces  left  with  common  yellow 
shellac,  which  takes  dark  in  the  photomicrograph.  Figure  98 
is  without  this.  In  Figures  96,  97,  which  are  both  from  cross 
sections,  but  from  different  teeth,  the  darker  portion  marked 
with  the  letter  x  is  the  injured  enamel,  while  that  portion  marked 
by  the  letter  e  is  uninjured.  In  each  case  the  border  line  between 
the  injured  and  uninjured  tissue  is  dark.  The  sections  from 
which  they  were  made  were  prepared  as  follows :  (1.)  The  cross 
section  of  the  tooth  was  ground  flat  and  polished.  (2.)  It  was 
then  placed  in  absolute  alcohol  for  twenty-four  hours  to  remove 
all  traces  of  water.  (3.)  It  was  placed  on  a  cover-glass  which 
was  covered  with  a  solution  of  ordinary  yellow  sheUac  in  abso- 


84  PATHOLOGY    OF    THE    HAKD    TISSUES   OF    THE    TEETH. 

lute  aleoliol,  which  had  been  filtered  to  free  it  from  all  insoluble 
particles.  (4.)  It  was  allowed  to  lie  in  an  abundance  of  the 
shellac  solution  for  several  hours.  (5.)  It  was  then  placed  on 
a  steel  disk  and  the  specimen  was  clamped  down  onto  the  cover- 
glass  with  a  heavy  weight,  the  excess  of  shellac  removed  and 
then  left  until  the  shellac  had  become  hard.  (6.)  The  cover-glass 
to  which  the  specimen  was  attached  was  then  cemented  to  a 
grinding-disk,  which  was  placed  in  the  grinding  machine  and  the 
specimen  ground  thin  enough  for  examination  with  a  twelfth- 
inch  immersion  lens.  (7.)  The  glass,  with  the  specimen,  was 
then  removed  from  the  grinding-disk  and  at  once  mounted  upon 
an  ordinary  slide,  using  for  the  purpose  xylol  balsam,  which 
does  not  dissolve  the  shellac  by  which  the  section  is  attached  to 
the  cover-glass.  In  this  way,  every  part  of  the  frail  tissue  is 
retained  in  its  normal  position.  From  the  photomicrograph  of 
this  the  engraving  is  made  without  the  slightest  retouching. 

It  is  seen  by  examination  of  the  illustrations  that  the 
spaces,  formed  between  the  enamel  rods  by  the  solution  of  the 
cementing  substance  by  the  acid  causing  the  injury  to  the  tissue, 
have  been  filled  by  the  shellac,  which  photographs  dark.  This 
divides  the  carious  area,  marked  by  the  letter  x,  sharply  from 
the  sound  tissue,  marked  by  the  letter  e,  and  displays  the  enamel 
rods,  or  the  undissolved  central  portions  of  them,  lying  in  a 
dark  field,  each  in  its  normal  position.  The  adjacent  undecayed 
enamel  does  not  absorb  the  shellac  and  remains  white.  In  Fig- 
ure 96  the  sound  enamel  shows  scarcely  a  trace  of  structure, 
while  in  Figure  97  the  enamel  rods  in  the  sound  tissue  are  very 
well  brought  out.  This  diiference  in  unetched  sound  enamel 
is  often  met  with.  In  both  specimens  the  area  decayed  is  also 
sharply  divided  from  the  normal  enamel  by  a  broad,  dark  band, 
which  occurs  in  many  specimens  in  which  no  shellac  has  been 
used,  as  will  be  seen  in  most  of  the  photomicrographs  of  decayed 
enamel  in  this  volume. 

If  we  examine  carefully  these  illustrations  as  to  the  com- 
parative sizes  of  the  enamel  rods  in  the  undecayed  and  the 
decayed  areas,  it  is  found  that  they  are  much  reduced  and  more 
slender  in  the  decayed  areas.  This  may  be  made  out  also  in  Fig- 
ure 98,  which  has  not  been  filled  by  shellac,  but  not  so  clearly. 
In  the  grinding  of  this  latter  specimen,  the  machine  was 
adjusted  to  stop  when  the  specimen  was  one  one-thousandth 
(1-1,000)  of  an  inch  thick.  Such  specimens  are  extremely  frail. 
When  the  solution  of  the  enamel  rods  has  gone  a  little  further 
than  shown  in  these  illustrations,  the  whole  structure  falls  to 


Fig.   98. 


Fig.    98.     A   photomicrograph   from   a   very   thin    section   of   carious   enamel   ground   on   the  cover 
glass  in  hard  balsam.  e.    Perfect  enamel.         x.  Carious  enamel.     The  line  between  the  sound  and 

carious  enamel  is  fairly  sharp,  and  follows  closely  the  length  of  the  enamel  rods. 

lib 


Fig.   100. 


i-plnt.w  to  in;^!?  ;th  ^,;''^A"  °^  }}""  "PP"'  ™°''"''*  ""''  b'<;">!Pids  of  the  right  side  in  their  norm.iI 
rnntaPt.  =nH  =r»a  f  '  "''  ""=  u°".  P.^'"  removed  to  show  the  interproximal  spaces,  interproximal 
fi??t  shmvinl  th„  h  1  "f  "■  ^PP™"'^''  ?f  'he  surfaces  of  the  teeth.  The  two  pictures  tak<i  together,  the 
hrst  showing  the  buccal  surfaces  and  the  second  the  occUisal  surfaces,  give  a  good  view  of  the  inter- 
hncco"ifL"'fl''''  ■';n"'-  °*  "-"f""^  occluso.gingivally,  and  breadth  of  near  approach  of  su??aces 
bucco-hngually,  with  their  variations.  They  also  show  the  openings  of  the  embrasures  buccally  and 
UnguaJly,  with  their  variations  in  depth. 


CABIES   OP   ENAMEL.  85 

pieces  at  a  touch,  and  most  generally  through  the  whole  thick- 
ness of  the  enamel  at  once.  This  seems  to  be  due  to  the  complete 
loosening  of  the  ends  of  the  rods  from  the  dentin.  In  unpro- 
tected places,  however,  such  as  decays  of  buccal  or  labial  sur- 
faces, and  decays  of  proximal  surfaces  in  which  there  has  been 
interference  by  the  crowding  of  food  through  the  contact,  a 
considerable  number  of  cases  are  found  in  which  the  outer  ends 
of  the  enamel  rods  are  broken  before  the  enamel  has  been  pene- 
trated. In  the  greater  number  of  cases,  however,  in  any  of  these 
positions,  a  considerable  solution  of  the  dentin  has  occurred  by 
the  acid  which  has  penetrated  through  the  enamel  before  any 
enamel  rods  have  fallen  away.  This  is  well  attested  in  many 
of  the  illustrations  presented. 

The  Relation  of  the  Occlusion  to  the  Localization 

OF  Caries. 

ILLUSTRATIONS:    FIGURES  99103. 

When  we  come  to  study  carefully  the  forms  of  the  teeth 
in  their  relations  to  each  other  as  they  stand  in  the  arch,  and 
their  uses  in  the  mastication  of  food,  we  find  that  there  are 
certain  points  or  areas  of  their  surfaces  that  are  comparatively 
free  from  rubbing,  or  abrasion,  while  much  the  larger  part  of 
the  tooth  surface  is  exposed  to  friction  and  washings  by  the 
fluids  in  the  mouth.  The  occlusal  surfaces  particularly  are 
exposed  to  severe  abrasion  in  the  mastication  of  food.  The 
lingual  surfaces,  both  above  and  below,  are  exposed  to  the  fric- 
tion of  the  tongue  and  of  the  food  that  is  washed  over  them 
during  mastication,  so  that  these  surfaces  are  fairly  well 
cleaned.  The  buccal  surfaces  are  less  exposed  to  friction  during 
mastication  and  to  washings  by  the  saliva  during  the  motions 
of  the  tongue,  cheeks  and  lips,  particularly  in  their  gingival 
thirds.  The  proximal  surfaces  are  shielded  from  abrasion  and 
from  washings  by  the  saliva  by  the  contact  and  areas  of  near 
approach  of  these  surfaces  with  adjoining  teeth.  Decays  begin- 
ning in  the  depths  of  the  pits  of  the  occlusal  surfaces  have  no 
opportunity  to  spread  upon  the  surface  of  the  enamel,  for  the 
reason  that  these  surfaces  are  so  continually  cleaned  by  abra- 
sion in  mastication  and  by  washings  by  the  saliva.  It  seems 
to  be  for  these  reasons,  principally,  that  decay  does  not  spread 
superficially  upon  these  surfaces.  It  is  prevented  by  the  forms 
and  the  uses  of  the  teeth.  It  seems  to  be  purely  these  local  con- 
ditions that  are  the  basis  of  the  strict  localization  of  the  begin- 


86  PATHOLOGY   OF    THE   HABD    TISSUES   OF    THE    TEETH. 

nings  of  dental  caries  in  certain  positions  in  the  enamel  to  the 
exclusion  of  all  others.  These  are  physical  conditions  controlling 
lodgments  of  debris.  They  are  also  physical  conditions  prevent- 
ing the  removal  of  anything  which  may  become  attached  to  the 
enamel  in  these  positions. 

If  we  study  the  relations  of  the  proximal  surfaces  of  the 
different  teeth  to  each  other,  we  find  that  various  forms  of  con- 
tact and  near  approach  of  these  surfaces  serve  to  shield  certain 
areas  from  all  friction  from  mastication  and  in  which  the  deposit 
of  a  very  little  gummy  material  will  shield  colonies  of  micro- 
organisms from  all  washings  by  saliva.  This  may  be  studied 
in  the  illustrations.  Figures  99,  100,  show  the  buccal  and  the 
occlusal  surfaces  of  the  upper  bicuspids  and  molars  as  they 
stand  in  the  arch.  The  teeth  are  in  the  same  relation  to  each 
other  in  each  figure.  The  soft  tissue  filling  the  interproximal 
spaces  has  been  removed  in  order  that  the  forms  of  these  may 
be  better  seen.  In  studying  the  buccal  view,  it  will  be  seen  that 
the  points  of  near  approach  of  surfaces  are  very  narrow  and 
rounded  in  form  from  occlusal  to  gingival,  so  that  the  actual 
touch  point  of  unworn  teeth  is  very  small,  like  that  of  two  mar- 
bles coming  in  contact,  while,  in  the  view  of  the  occlusal  surfaces, 
the  points  of  near  approach  of  the  teeth  to  each  other  are  shown 
to  be  very  much  broader  in  the  bucco-lingual  direction. 

The  decays  in  the  proximal  surfaces  of  the  bicuspids  and 
molars,  in  Figures  86-91,  inclusive,  correspond  in  form  with  the 
areas  of  near  approach  of  the  surfaces  of  the  teeth  so  closely 
and  so  constantly  that  we  must  connect  these  relations  as  cause 
and  effect,  controlling  both  the  localization  and  superficial  form 
of  the  beginning  and  spreading  of  caries  in  the  enamel.  To  gain 
correct  expressions  of  this,  the  study  must  be  confined  to  those 
beginnings  of  decay  that  have  not  yet  penetrated  the  enamel, 
or  in  which  the  enamel  rods  have  not  yet  fallen  out,  for,  with  the 
breaking  away  of  the  enamel  after  decay  of  dentin  has  begun, 
the  particular  form  of  the  beginning  upon  the  surface  of  the 
enamel  is  often  quickly  lost. 

A  study  of  the  forms  of  the  surfaces  making  the  contact 
of  different  teeth  as  seen  in  the  occlusal  view,  will  show  great 
variations  in  the  bucco-lingual  length  of  near  approach  of  these 
surfaces.  The  area  of  near  approach  of  surfaces  is  much  longer 
bucco-lingually  between  the  second  bicuspid  and  the  first  molar 
than  that  between  the  two  bicuspids.  Therefore,  a  beginning 
decay  between  the  second  bicuspid  and  first  molar  will  spread 
and  become  longer  bucco-lingually  in  these  than  a  beginning 


CAEIES   OF   ENAMEL.  87 

decay  would  do  between  the  two  bicuspids.  The  differences  in 
this  respect  among  the  teeth  of  the  same  mouth,  and  especially 
among  the  teeth  of  different  mouths,  are  very  great. 

As  this  study  of  forms  of  contact  and  near  approach 
accounts  for  the  differences  seen  in  forms  of  decay  in  tliis 
respect,  as  shown  in  illustrations  given  of  the  bicuspids  and 
molars.  Figures  86-91,  inclusive,  it  also  accounts  for  the  differ- 
ences shown  of  the  breadth  of  decay  in  illustrations  made  from 
cross  sections  of  the  teeth,  Figures  92-95,  as  compared  with 
sections  made  lengthwise  of  the  tooth.  A  section  made  length- 
wise of  a  tooth  may  show  a  very  narrow  injury  to  the  enamel, 
while,  if  the  section  were  made  crosswise  of  the  tooth,  cutting 
through  the  length  of  the  injury,  it  would  show  a  very  broad 
beginning  of  decay.  This  will  be  seen  more  clearly  by  a  com- 
parative examination  of  sections  cut  in  these  different  directions 
which  show  the  great  difference  in  the  form  and  extent  of  the 
injury  to  the  enamel.  This  will  be  appreciated  by  comparing 
the  cross  sections.  Figures  92-95,  with  the  photographs  of  split 
teeth,  Figures  107, 108,  112,  113, 117. 

The  embrasures,  or  the  openings  formed  on  the  buccal  and 
on  the  lingual  by  the  rounding  of  the  surfaces  of  the  teeth  away 
from  each  other,  vary  greatly  in  depth  among  the  different 
embrasures  of  the  same  moutia,  and  particularly  they  vary  in 
depth  among  the  teeth  of  different  persons,  owing  to  the  forms 
of  the  teeth  and  the  form  and  prominence  of  the  proximal  con- 
tact points.  It  must  be  remembered  that  in  normal  conditions 
in  young  people,  the  interproximal  space  is  filled  with  gum 
tissue  to,  or  very  nearly  to,  the  contact  point,  and  that  the  gum 
tissue  arches  up  to  this  from  the  buccal  and  the  lingual.  In 
studying  this,  it  will  be  found  that  the  beginning  of  decay  is 
close  to  the  line  of  the  margin  of  this  arch  of  gum  tissue,  and  it 
does  not  spread  to  the  gingival  unless  the  gum  tissue  has  been 
pushed  away  by  lodgments  of  food  between  the  teeth.  There- 
fore, unless  lodgments  of  food  have  occurred,  the  forms  of 
beginning  decay  will  retain  that  narrowness  from  occlusal  to 
gingival  that  has  been  shown,  and  the  spreading  bucco-lingually 
will  generally  coincide  with  the  length  of  the  close  approach  of 
the  surfaces  to  each  other. 

If  we  study  the  teeth  in  their  occlusion  under  normal  con- 
ditions, we  will  find  a  provision  of  very  considerable  importance 
in  the  relation  of  the  cusps  of  the  upper  teeth  to  the  embrasures 
between  the  lower  teeth,  and,  vice  versa,  the  arrangement  of 
the  cusps  of  the  lower  teeth  with  respect  to  the  embrasures  in 


88  PATHOLOGY   OF   THE   HABD   TISSUES   OF   THE   TEETH. 

the  upper  teeth.  This  -will  be  seen  in  Figure  101.  Beginning 
with  the  third  molars,  we  find  that  the  cusp  of  the  lower  third 
iQolar  occludes  directly  under  the  embrasure  between  the  second 
and  third  molars  of  the  upper  jaw  and  will  force  food  through 
that  embrasure  especially,  while  the  second  molar  of  the  upper 
jaw  has  its  distal  cusp  over  the  embrasure  between  the  second 
and  third  molars  of  the  lower  jaw  and  will  force  food  through 
it.  This  arrangement  is  repeated  among  all  the  molars  and 
bicuspids.  The  result  is  that,  in  mastication,  the  food  is  caused 
to  run  through  the  embrasures  by  the  crushing  action  of  the 
teeth.  The  effect  of  this  arrangement  will  perhaps  be  better 
understood  by  comparison  with  the  occlusal  surfaces  of  the  same 
teeth  as  seen  in  Figures  102,  103,  noting  carefully  the  forms  of 
the  individual  embrasures  and  their  variations.  This  abrasive 
action  by  the  food  is  increased  by  the  cheeks  and  tongue  also 
pressing  upon  the  food  laterally,  causing  it  to  be  crushed  down 
over  the  buccal  and  lingual  surfaces  of  the  teeth,  and  more  par- 
ticularly through  these  embrasures.  In  fact,  this  lateral  pres- 
sure on  the  food  is  an  endeavor  to  hold  it  between  the  occlusal 
surfaces  of  the  teeth.  The  result  is  that  the  food  is  forced 
through  the  embrasures  especially,  causing  it  to  rub  the  angles 
of  the  teeth  from  their  occlusal  surfaces  to  the  gum  margin. 

This  abrasive  action  of  the  food  serves  to  limit  sharply  the 
distance  that  attached  colonies  of  microorganisms  may  spread 
toward  the  buccal  or  lingual  angles  of  the  teeth  because  of  their 
removal  from  the  surfaces  by  the  passing  of  food  through  these 
embrasures  during  mastication.  It  also  explains  another  fact 
of  great  importance  in  the  treatment  of  caries  of  the  teeth  by 
filling,  for  it  was  found  by  actual  count  of  ten  thousand  persons 
examined  that  only  in  about  one  case  per  thousand,  decay  was 
found  to  have  spread  superficially,  or  upon  the  surfaces  of  the 
teeth,  across  the  angles.  Therefore,  near  to,  or  along  these 
angles,  is  the  safest  place  to  lay  cavity  margins. 

CaBIES     never    begins    on     THE    ANGLES    OF    THE    TEETH    UOr 

spreads  superficially  past  these  angles  in  any  case  in  which  the 
teeth  are  in  normal  relations  and  the  person  is  making  active 
use  of  them  in  mastication ;  this  may  be  stated  without  fear  of 
successful  denial.  All  of  the  cases  of  such  spreading  that  have 
come  under  my  observation  in  twenty-five  years  of  close  study 
of  this  point,  have  been  in  persons  who  have  practically  ceased 
to  use  their  teeth  in  the  mastication  of  food  because  of  some 
interference.  This  has  generally  been  sensitiveness  of  exposed 
pulps  in  decayed  teeth,  and  at  the  same  time  the  persons  had 


Fig.  101.  Photograph  of  the  teeth  in  normal  occlusion,  including  the  alveolar  processes  and 
bones.  This  is  given  as  a  study  of  the  normal  relations  of  the  cusps  of  the  teeth  of  the  upper  arch 
to  the  embrasures  of  the  lower,  and  the  relations  of  the  cusps  of  the  lower  teeth  to  the  embrasures  of 
the  upper.  It  will  be  seen  that  among  the  bicuspids  and  molars  this  relation  is  constantly  such  as  to 
force  food  through  these  embrasures  in  chewing. 


[•'10.    102. 


Fia.   103. 


Figs.  102,  103.  Photographs  of  the  upper  and  lower  teeth  shown  in  Figiire  101.  In  these  it  will 
be  seen  that,  while  the  molars  and  bicuspids  are  in  normal  occlusion,  the  left  lateral  incisor  is  miss- 
ing in  the  upper  jaw.  This  has  forced  an  irregularity  of  the  incisors  of  the  lower  jaw.  These  give  an 
additional  study  of  contacts,  embrasures  and  near  approach  of  areas  of  the  proximal  surfaces. 


CABIES    OF    ENAMEL.  89 

become  entirely  careless  as  to  artificial  cleaning.  The  study  of 
this  phase  of  the  spreading  of  caries  and  its  limitations  is  of  the 
utmost  importance.  The  student  and  the  practitioner  should  be 
continually  studying  it  in  the  mouths  of  his  patients,  making  out 
carefully  areas  of  spreading  decay  and  their  normal  limitations 
under  the  conditions  which  he  finds.  This,  if  carefully  carried 
out,  will  serve  as  a  guide  of  great  importance  in  the  extensions 
necessary  in  the  preparation  of  cavities  to  prevent  recurrence 
of  decay  about  cavity  margins. 

In  the  consideration  of  the  beginning  of  caries  of  the  enamel 
with  reference  to  treatment,  it  may  be  stated,  as  a  fundamental 
proposition,  that  the  nidus  of  each  beginning  of  caries  will  he 
found  at  that  particular  point  on  the  surface  of  the  tooth 
attacked,  or  that  may  he  attached  in  the  future,  that  offers  the 
best  position  for  the  lodgment  and  undisturbed  growth  of  colo- 
nies of  microorganisms.  These  colonies  and  the  caries  will 
spread  superficially  on  the  surface  to  those  lines  where  their 
further  spread  is  limited,  (1)  by  the  position  of  normal  gum 
tissue;  (2)  by  abrasion  of  mastication  by  excursions  of  food 
through  the  embrasures;  or  (3),  by  artificial  cleaning.  When 
this  nidus  is  destroyed  by  the  falling  away  of  the  enamel  rods 
because  of  caries  of  the  dentin,  before  such  spreading  has 
reached  its  limit,  as  often  happens,  the  conditions  are  usually 
so  changed  that  the  growth  of  colonies  on  the  surface  of  the 
enamel  is  prevented.  This  at  once  limits  further  superficial 
spreading  buccally  and  lingually  on  the  lines  thus  far  illustrated. 
Further  superficial  spreading  gingivally,  may  or  may  not  occur, 
as  will  be  illustrated  later.  The  lateral  superficial  spreading 
seems  to  be  stopped  by  the  frequent  catching  of  stringy  foods 
on  the  roughened  area  and  the  worry  of  the  parts  in  its  removal, 
or  by  the  frequent  forcing  of  these  lodgments  further  to  the 
gingival  at  each  meal  time.  In  many  of  the  cases  the  loss  of  the 
central  and  best  attachment  of  the  organisms  may  of  itself  be 
sufficient  to  produce  this  effect.  However  this  may  be,  much 
careful  observation  shows  that  after  the  opening  of  the  cavity 
this  stoppage  occurs  in  many  cases.  But  if  a  good  and  perfect 
filling  is  made,  restoring  the  original  form  and  conditions  with- 
out reference  to  the  possible  further  spreading  of  the  growth  of 
colonies  of  microorganisms,  such  filling  will  reestablish  the  nidus 
for  growth  and  this  will  recur  on  the  filling  and  extend  to  the 
full  limit  that  it  might  have  done  if  the  original  nidus  had  not 
been  destroyed,  thus  reestablishing  caries  beyond  the  mar^ns 
of  the  filling.    In  this  way,  a  well-made  filling  in  the  mechanical 

12 


90  PATHOLOGY    OF    THE    HAKD    TISSUES   OF    THE    TEETH. 

sense,  restoring  the  original  contour  perfectly  but  without  ref- 
erence to  the  superficial  spreading  of  caries,  may  become  the 
cause  of  wider  spreading  of  decay  on  the  surface  than  would 
have  occurred  without  it.  Further,  in  practice,  it  will  be  found 
that  when  proximal  fillings  are  made  without  separating  the 
teeth  to  gain  room  for  the  finishing  of  the  fillings  to  the  full 
original  contour,  with  the  original  fullness  of  the  contact  points, 
but  necessarily  losing  a  little  of  the  original  mesio-distal  breadth, 
the  area  of  near  approach  of  the  proximal  surfaces  is  increased, 
the  embrasures  are  made  shallower  and  the  opportunity  for 
recurrence  of  caries  at  the  bucco-gingival  and  linguo-gingival 
angles  of  fillings  is  increased. 

Penetration  of  the  Enamel  in  Buccal  and  Labial  Surfaces. 

Caries  beginning  in  the  buccal  and  labial  surfaces  presents 
the  same  characters  as  to  penetration  of  the  enamel  and  spread- 
ing in  definite  directions  as  decays  beginning  in  the  proximal 
surfaces.  In  this  case  the  line  of  beginning  is  along  the  free 
margin  of  the  gum  in  the  middle  third  of  the  surface  mesio- 
distally.  The  lines  of  extension  in  spreading  are  toward  the 
mesial  and  the  distal  angles  of  the  tooth.  The  beginning  of  these 
decays  often  forms  a  narrow  whitened  line,  the  length  of 
which  is  from  mesial  to  distal.  These,  taken  with  the  decays  of 
the  proximal  surfaces,  tend  to  form  lines  encircling  the  teeth 
along  the  free  margins  of  the  gum.  This  is  very  generally 
defeated  by  the  failure  to  spread  across  the  angles  of  the  teeth. 
But  when  the  angles  are  passed  and  when  connected  by  decay 
on  the  lingual  surfaces,  which  sometimes  occurs,  the  complete 
girdling  of  the  teeth  is  accomplished.  Frequently  we  may  find, 
in  the  first  beginning  of  the  decay  on  buccal  surfaces,  several 
starting  points  which  later  run  together,  forming  a  continuous 
line  of  whitened  enamel.  This  gives,  in  cross  sections  of  the 
tooth,  appearances  almost  exactly  similar  to  those  shown  in 
Figures  92-95,  inclusive.  As  the  very  general  rule,  the  extension 
of  decay  on  the  surface  of  the  enamel  is  stopped  at  the  mesial 
and  distal  angles  of  the  surface. 

T^Hiile  these  decays  occur  in  a  much  less  number  of  persons 
than  proximal  decays,  they  often  attack  tooth  after  tooth  in 
quick  succession,  and  progress  very  rapidly  in  the  enamel, 
destroying  considerable  areas  of  enamel  tissue.  They  become 
wide-open  cavities,  and,  in  the  mouths  that  have  very  little  care, 
are  apt  to  run  a  rapid  course. 

This  subject  will  be  presented  in  greater  detail  under  the 
heading,  "Caries  as  a  Whole," 


Fia.  104.  l'hotogr;iph  of  a  split  upper  first  iimlnr  with  an  occlusal  decay  of  ordinary  form. 
Note  a  small  beginning  of  decay  of  rnamcl  in  the  distal  surface,  and  a  decay  beginning  in  the  cemen- 
turn.  This  lallcr  is  characteristic  of  decays  which  occur  because  of  crowding  of  food  into  the  inter- 
proximal space,   with   resulting  absorption  of  the  interproximal   gimi   tissue. 


Fias.  lOS,  100.  Photographs  showing  (ieciiys  in  occhisul  pits,  in  wliicli  the  opening  Uirough  the 
enamel  has  become  larger  and  the  decayed  areas  are  ot  less  depth  in  proportion  to  their  breadth. 
Some  proximal  decays  are  also  shown. 


CABIES  AS  A    WHOLE.      ITS   CLINICAX   FEATUBEa  91 


CARIES  AS  A  WHOLE.    ITS  CLINICAL  FEATURES. 

In  the  further  consideration  of  the  injuries  inflicted  by 
caries  of  the  teeth,  we  may  include  caries  of  both  the  enamel 
and  dentin.  In  this  we  may  consider  the  processes  as  a  whole, 
noticing  the  various  characters  presented  in  the  beginning  and 
progress,  controlled  purely  by  local  or  clinical  conditions.  These 
conditions  have  no  special  signification  as  to  immediate  or  remote 
cause  of  caries  further  than  location  or  condition  of  tissue  which 
may  influence  the  action  of  these  causes.  Yet  these  causes  which 
are  brought  into  action,  seemingly  because  favorable  conditions 
for  their  active  development  have  been  i^resented,  can  not  be 
lost  sight  of  in  any  consideration  whatever.  It  may  truly  be  said 
that,  without  the  presence  of  the  principal  causes  no  decay  could 
occur,  and  also  that,  without  reasonably  favorable  conditions  for 
their  action,  these  causes  would  not  produce  decay. 

This  may  be  said  to  constitute  the  clinical  features  of  dental 
caries,  and  in  its  consideration  frequent  reference  will  be  made 
to  the  clinical  management  of  cases.  One  of  the  surprising 
features  of  the  study  of  dental  caries  that  comes  sharply  in  view 
when  the  history  of  the  development  of  our  knowledge  of  it  is 
closely  scanned,  has  been  its  complete  divorcement  from  all 
clinical  consideration.  It  seems  to  be  correct  to  say  that  a  large 
number  of  even  the  most  earnest  workers  in  dentistry  are  doing 
their  work  of  treatment  by  rote,  without  any  proper  thought 
of  the  relations  which  their  plan  of  treatment  may  bear  to  the 
conditions  that  have  localized  the  decay  being  treated  at  that 
particular  spot,  and  making  inadequate  provision,  or  too  often 
no  provision  at  all,  for  the  prevention  of  a  recurrence  of  the 
trouble.  It  is  only  recently  that  there  has  been  any  special  study 
given  to  the  conditions  of  the  beginning  of  caries  of  the  enamel, 
which  really  is  the  all-important  question  in  the  study  of  dental 
caries  considered  from  the  clinical  standpoint.  One  of  the 
noblest  pieces  of  scientific  work  in  pathology  was  Dr.  W.  D. 
Miller's  investigation  of  dental  caries.  It  not  only  developed 
the  questions  at  issue,  but  completed  the  investigation  so  that 
the  rest  of  us,  in  repeating  his  experimental  work,  could  only 
say,  well  and  correctly  done.  But  this  investigation  was  con- 
fined exclusively  to  the  immediate  active  cause  of  caries  as  it 
occurs  in  dentin.    Decay  of  enamel,  or  the  conditions  localizing 


92  PATHOLOGY   OF    THE    HARD    TISSUES    OF    THE    TEETH. 

beginnings  of  this,  which  constitutes  the  initial  lesion,  without 
which  caries  of  dentin  never  occurs,  was  left  untouched.  These 
constitute  the  principal  clinical  features  of  the  disease  we  are 
treating.  Our  knowledge  of  them  is,  as  yet,  but  partially  devel- 
oped, particularly  in  that  the  systemic  conditions  of  suscepti- 
bility and  immunity  are  but  indefinitely  known;  and  observers 
do  not  yet  agree  as  to  the  especial  relations  of  acid  saliva  and  of 
microorganisms  to  the  particular  processes  in  the  earlier  parts 
of  the  beginning  of  caries  of  enamel. 

Occlusal  Sukface  Decays  in  Molabs. 

ILLUSTRATIONS:    FIGURES  68-71,  104-106. 

Pbincipal  clinical  features:  (1.)  Beginning  in  pits, 
absence  of  superficial  spreading.  (2.)  Rapid  burrowing  along 
the  dento-enamel  junction.  (3.)  Spreading  in  the  dentin  in  true 
conical  form.  (4.)  Great  softening  of  dentin  in  advance  of  the 
decomposition  of  the  organic  matrix.  (5.)  Very  large  decays 
often  occurring  while  the  opening  to  the  surface  remains  small. 
These  characters  are  common  to  decays  beginning  in  pits  and 
fissures  wherever  found. 

The  conical  form  of  decays  of  dentin  beginning  in  pits,  in 
the  occlusal  surface  or  elsewhere,  the  spreading  along  the  dento- 
enamel  junction,  and  the  absence  of  spreading  superficially  on 
the  surface  of  the  enamel,  have  been  considered  in  previous 
articles  and  some  principal  illustrations.  Figures  68-71,  given. 
For  the  further  illustration  of  the  clinical  features,  the  Figures 
104-106,  inclusive,  are  here  provided.  It  will  be  seen  that  Figure 
104  and  other  figures  of  this  group  show  the  same  form  of 
decayed  area  more  or  less  perfectly,  the  detail  being  different 
in  some  degree  on  account  of  size  of  the  decayed  area  or  the 
particular  form  of  the  surface  of  the  tooth  about  it.  In  each 
case  illustrated,  the  direction  of  force  in  tlie  use  of  the  chisel 
in  opening  the  cavity  so  as  to  fully  uncover  the  area  of  decay, 
may  be  studied.  The  case  illustrated  in  Figure  104,  considering 
the  tooth  as  a  whole,  is  complicated  by  two  other  decays,  both 
of  them  in  the  distal  surface;  one  a  very  shallow  decay,  begin- 
ning in  the  enamel  at  the  usual  point  of  beginning  decays,  and 
the  other  a  decay  beginning  in  the  cementum  and  penetrating 
into  the  dentin  at  the  gingival  line.  This  latter  is  a  serious 
complication  in  the  clinical  sense,  which  has  arisen  from  neglect 
of  the  leakage  of  food  into  the  interproximal  sjjace.  In  Figures 
105,  106,  the  openings  through  the  pits,  in  wliich  the  decay  has 


CABIES    AS   A    WHOLE.       ITS    CLINICAL,   FEATURES.  93 

begun,  are  unusually  large.  This  has  occurred  by  the  breaking 
away  of  the  enamel  about  the  pit  much  earlier  in  the  progress 
of  the  decay  than  usual.  In  response  to  this  early  widening  of 
the  pit,  giving  a  greater  opportunity  for  washing  out  acids 
formed  in  the  dentin,  the  penetration  of  the  dentin  presents  a 
much  less  pointed  cone,  the  penetration  is  less  in  proportion  to 
the  breadth  than  in  cases  in  which  there  is  less  breaking  of 
enamel  about  the  pit.  This  is  seen  most  distinctly  in  Figure  106. 
In  studying  these  illustrations,  one  must  divide  the  area  of  actual 
decay  from  the  cloud  (hyaline  area)  stretching  away  toward  the 
pulp.  In  Figure  105  there  is  really  very  little  decay  of  dentin. 
The  triangular  (in  section)  cloud  stretching  toward  the  pulp 
chamber  is  not  softened  dentin.  In  Figure  106  the  area  of  decay 
is  more  definitely  outlined  by  the  distinctly  darkened  area  which 
is  flattened  or  rounded  rather  than  in  the  typical  conical  form. 
This  is  characteristic  of  a  wide  opening  through  the  enamel.  The 
rate  of  progress  of  decay  is  quite  apt  to  be  greater  where  it  is 
hidden  away  under  the  overlapping  enamel  than  in  the  central 
parts.  The  tendency,  therefore,  is  to  form  broad,  flat  cavities. 
Both  of  these  cases,  considering  each  tooth  as  a  whole,  are  com- 
plicated by  proximal  decays.  On  account  of  ease  of  access  and 
the  absence  of  the  tendency  to  superficial  spreading  of  decay, 
these  cavities  and  pit  cavities,  wherever  they  occur,  are  the 
simplest  of  cavities  in  the  clinical  sense.  The  only  thing  requir- 
ing special  attention  outside  of  the  area  of  decay  and  its  full 
exposure  by  trimming  away  the  undermined  enamel,  is  to  see 
to  it  that  all  grooves  are  cut  out  to  such  a  point  as  wiU  give 
opportunity  for  a  smooth  finish  of  the  filling. 

Proximal  Surface  Decays  in  Molaes. 

ILLUSTRATIONS:    FIGURES  107-111. 

Principal  clinical  features:  (1.)  The  beginning  decays 
of  this  class  are  hidden  from  view  in  the  proximal  surfaces  of 
the  teeth,  making  their  early  discovery  difficult.  (2.)  A  tendency 
to  wide  spreading  on  the  surface  of  the  enamel,  bucco-lingually, 
making  extension  for  prevention  necessary  in  filling  operations. 
(3.)  Tendency  to  the  early  undermining  of  the  marginal  ridge 
by  the  extension  of  decay  along  the  dento-enamel  junction  and 
the  exposure  of  the  cavity  by  its  breakage.  (4.)  Wide  secondary 
spreading  gingivally  in  a  considerable  number  of  cases  which 
is  liable  to  be  overlooked  in  the  preparation  of  cavities.  (5.) 
Recurrence  of  decay  at  the  bucco-gingival  and  linguo-gingival 


94  PATHOLOGY   OF   THE   HABD   TISSUES   OF   THE   TEETH. 

angles  of  fillings  when  judicious  extension  for  its  prevention  is 
neglected.  (6.)  Recurrence  at  the  gingival  margins  of  fillings 
where  contacts  are  of  bad  form,  allowing  food  to  leak  into  the 
interproximal  space.  (7.)  Hence  the  requirement  that  correct 
forms  be  given  contact  points  in  the  finishing  of  fillings. 

The  conical  form  of  cavities  in  the  dentin  is  a  little  different 
in  proximal  cavities,  where  seen  in  sections  cut  mesio-distally, 
from  those  in  occlusal  surfaces,  because  of  the  difference  in  the 
trend  of  the  dentinal  tubules  from  the  line  of  the  dento-enamel 
junction  toward  the  pulp  of  the  tooth.  It  is  still  a  cone,  how- 
ever, with  its  base  placed  diagonal  to  its  length,  or  in  section  it 
is  a  triangle,  having  one  of  its  basal  angles  obtuse.  The  tendency 
to  this  form  is  best  displayed  in  the  decays  in  Figure  110.  In 
general,  there  is  a  greater  tendency  to  rounding  of  the  general 
line  of  invasion  of  dentin  than  is  seen  in  the  decays  beginning 
in  occlusal  surfaces.  There  is  the  same  tendency  to  wide  soften- 
ing of  the  dentin  more  rapidly  than  the  decomposition  of  the 
organic  matrix  when  the  opening  in  the  enamel  is  small,  as  is 
seen  elsewhere;  but  this  disappears  when  the  enamel  breaks 
away,  exposing  the  cavity  to  the  occlusal  surface.  As  the  time 
in  relation  to  the  progress  of  the  decay  at  which  this  breakage 
of  the  enamel  occurs  is  very  variable,  extensive  burrowing  with 
large  amounts  of  softened  dentin  is  liable  to  be  found  unex- 
pectedly in  that  which  seemed,  upon  superficial  examination, 
to  be  a  small  cavity.  The  large  proximal  decays  in  Figures  110 
and  111  show  something  of  the  extent  to  which  these  cavities 
may  burrow  before  the  marginal  ridge  breaks  away,  exposing 
them  to  the  occlusal  surface. 

A  lower  molar  is  shown,  in  Figure  107,  with  a  mesial  surface 
decay  and  a  distal  surface  decay,  both  of  which  are  excellent 
types  of  the  early  beginnings  of  caries  in  these  surfaces.  In 
that  in  the  mesial  surface,  the  decay  has  just  passed  through 
the  enamel,  no  enamel  rods  having  yet  fallen  away.  In  the  distal 
surface  the  enamel  rods  have  fallen  out  and  the  extension  of 
caries  along  the  dento-enamel  junction  is  making  progress.  This 
is  seen  best  in  the  picture  to  the  right.  From  this  the  hyaline 
zone  stretches  away  to  the  pulp  chamber.  This  picture  is  a  most 
excellent  study.  It  is  well  to  note  the  small  amount  of  dentin 
between  the  occlusal  surface  and  the  pulp  in  this  case,  and  also 
the  great  extension  of  the  mesial  marginal  ridge  of  the  pulp. 
The  frequent  extension  of  the  mesio-buccal  horn  of  the  pulp  in 
both  upper  and  lower  first  molars  is  a  menace  in  cavity  prepara- 
tion that  should  be  carefully  guarded  against  when  possible,  by 


Fig.    108. 


Fig.  107.  A  pliotograph  giving  an  excellent  showing  of  a  mesial  and  a  distal  decay  in  a  lower 
molar  that  have  made  but  little  advancement.  The  two  halves  of  the  tooth  are  shown,  giving  two 
views  of  each  decay.  In  the  decay  in  the  mesial  surface  the  enamel  rods  have  not  yet  fallen  out  from 
any  part.  The  enamel  has  been  penetrated,  however,  and  in  the  half  on  the  left  side  some  solution  of 
the  dentin  is  apparent.  In  this,  another  feature  not  so  frequently  met  with,  is  the  compression  of  the 
decayed  area  by  contact  with  the  next  tooth,  which  is  apparent  in  both  halves  but  is  most  prominent 
in  the  half  on  the  left  side.  It  is  not  uncommon  to  find  a  decay  that  has  progressed  about  as  this 
has  done  (but  situated  just  to  the  gingival  of  the  contact),  swollen  so  as  to  have  become  flattened 
against  the  proximating  tooth  or  even  to  take  its  form  for  a  space.  But  for  the  area  of  decay  to 
occupy  the  contact  point  as  in  this  case  is  infrequent.  In  the  decay  in  the  distal  surface,  the  enamel 
rods  have  fallen  out  of  the  central  area,  and  in  the  half  on  the  right  side,  there  is  an  excellent  show- 
ing of  the  projection  of  decay  along  the  deiito-enamel  junction.  The  illustration  is  also  an  interesting 
one  because  of  the  showing  of  the  unusual  nearness  of  the  pulp  Ui  the  occlusal  surface  and  the  danger 
of  exposing  the  mesial  marginal  ridge  of  the  pulp,  or  horn  of  the  pulp. 

Fig.  108.  An  upper  first  molar  with  a  distal  decay  which  has  made  considerable  progress,  ana 
has  undermined  the  distal  marginal  ridge. 


Mm  i 


FlQ.     111. 


Fig.  109.  This  photograph  discloses  tliree  decays;  one  in  the  mesial  surface,  one  in  the  distal 
surface,  ami  one  in  the  occlusal  surface.  Tlie  decay  in  the  distal  surface  is  not  well  sliown  because  of 
the  loss  of  a  part  of  the  enamel.  The  decay  in  the  mesial  surface  is  cut  to  one  side  of  its  central 
area  and  shows  the  undermining  of  the  enamel  buccally  beyond  the  area  of  penetration  of  the  enamel, 
and  shows  well  the  area  of  whitened  bacliward  decay  of  the  enamel.  The  extraordinary  prolongation 
of  the  mesiobuccal  horn  of  the  pulp  is  also  an  interesting  feature  of  the  specimen. 

Fig.  110.  The  decay  on  the  right  side  of  the  illustration  shows  a  very  prominent  clouding 
extending  to  the  pulp.  This  also  shows  particularly  well  the  form  of  the  clouded  area,  with  the  base  of 
the  cone  placed  diagonal  to  its  length,  caused  by  the  relation  of  the  direction  of  the  dentinal  tubules 
to  the  proximal  surfaces.  The  actual  decay  of  the  dentin  in  this  case  is  marked  by  the  very  dark 
area  about  the  small  opening  in  the  enamel.  The  spreading  along  the  dento-enamel  junction  is  very 
wide.  The  decay  in  the  mesial  surface  has  exposed  the  pulp  before  the  mesial  marginal  ridge  has 
broken  so  as  to  expose  the  cavity. 

FiQ.  111.  This  tooth  has  an  unusually  heavy  enamel  cap.  This  seems  not  to  have  been  any  bar 
to  the  penetration  of  caries,  but  has  prevented  the  breaking  of  the  marginal  ridge  disclosing  the 
cavity  to  the  occlusal  surface,  though  it  is  extensively  undermined. 


CARIES   AS   A    WHOLE.       ITS    CLINICAL,   FEATURES.  95 

avoiding  cutting  through  its  recessional  line.  This  recessional 
line  is  usually  nearly  a  direct  line  from  the  point  of  the  cusp 
to  the  present  location  of  the  point  of  the  horn  of  the  pulp.  Where 
the  point  of  the  horn  may  be  located  along  that  line  in  any  indi- 
vidual case  can  not  be  told  in  advance,  but  that  it  will  not  be 
much  out  of  that  line  is  a  certainty.  When  it  is  possible,  cutting 
that  line  should  be  avoided. 

In  this  group  of  pictures,  and  in  the  next  following,  the 
clouded  areas  stretching  away  from'  the  areas  of  decay  toward 
the  pulp  are  particularly  prominent.  The  best  examples  are  in 
Figures  110,  113  and  117.  It  is  an  almost  constant  appearance 
in  some  form,  even  in  the  freshest  decays,  after  the  acid  has 
begun  to  dissolve  the  calcium  salts  of  the  dentin,  but  it  never 
appears  before  the  enamel  has  been  penetrated.  It  was  first 
described  by  John  Tomes  and  by  him  was  called  the  hyaline  area 
in  advance  of  actual  caries.  It  finally  became  known  as  the 
hyaline  area  of  Tomes.  At  first  Mr.  Tomes  supposed  this  was 
caused  by  an  increased  deposit  of  calcium  salts,  filling  the  den- 
tinal tubules.  While  the  chemico-vital  theory  of  caries  was  held, 
this  was  looked  upon  as  an  effort  to  bar  the  further  progress 
of  caries  by  building  against  it.  With  further  studies,  this  expla- 
nation became  untenable.  It  now  seems  more  probable  that  it 
is  caused  by  the  death  of  many  of  the  dentinal  fibrils.  The 
appearance  differs  much  in  different  cases.  It  may  be  either 
a  cloud  fringed  with  white,  or  a  white  area  fringed  with  cloud, 
an  irregular  distribution  of  these,  or  it  may  be  wholly  of  the 
one  or  the  other.  It  appears  to  the  best  advantage  in  photo- 
graphs of  split  teeth  by  reflected  light,  and  its  prominence  in  the 
photograph  depends  much  upon  the  condition  of  the  dentin  as  to 
translucence  at  the  moment  of  photographing.  A  freshly  cut 
tooth  is  apt  to  show  it  best,  and,  if  it  is  photographed  at  once 
on  being  removed  from  water,  the  surface  being  simply  wiped 
dry,  the  appearance  will  be  much  stronger  than  it  will  be  if 
the  tooth  has  been  allowed  to  dry.  Therefore,  it  has  happened 
occasionally  in  the  pictures  presented  that  the  photograph  of 
one  of  the  halves  of  a  tooth  has  shown  this  strongly,  while  the 
other  half  of  the  same  tooth  has  scarcely  shown  it  at  all.  How 
much  actual  injury  to  the  tooth  is  done  by  that  influence  which 
causes  this  hyaline  zone  can  not  well  be  told.  That  there  is  a 
distinct  injury  is  certainly  true.  It  seems  now  that  the  most 
rational  explanation  is  that  in  this  zone  many  of  the  dentinal 
fibrils  are  dead  from  the  irritation  caused  by  the  progress  of 
caries.    If  this  is  true,  the  extension  of  this  to  the  pulp  may  be 


96  PATHOLOGY   OF    THE    HAKD   TISSUES   OF    THE   TEETH. 

the  cause  of  the  hyperaemia  of  the  pulp  that  so  often  occurs  in 
carious  teeth  before  the  pulp  has  become  involved  or  exposed 
to  the  actual  carious  process. 

In  studying  the  decays  of  this  tooth,  Figure  107,  or  others 
of  this  group,  it  will  be  seen  that  any  effort  to  prepare  these 
smaller  cavities  as  simple  proximal  cavities,  would  inevitably 
produce  conditions  which  would  cause  failure  of  the  fillings, 
for  the  reason  that  they  are  situated  so  close  to  the  marginal 
ridges  that  the  enamel  rods  slope  very  much  toward  the  ridge. 
Further  cutting  in  that  direction  to  obtain  a  clean  enamel  wall, 
or  to  remove  the  decay  projecting  along  the  dento-enamel  junc- 
tion, would  bring  the  margin  of  the  filling  to  an  impossible  point, 
because  of  the  direction  of  the  enamel  rods.  Therefore,  the 
marginal  ridge  should  be  cut  through  and  anchorage  made  in 
the  form  of  a  step  in  the  occlusal  surface. 

This  is  more  sharply  illustrated  in  the  undermining  of  the 
distal  marginal  ridge  in  Figure  108,  in  which  decay  has  made 
a  little  further  progress.  In  such  positions,  this  undermining 
is  generally  done  very  early  in  the  progress  of  the  decay  and 
the  marginal  ridge  breaks  away,  exposing  the  cavity  corre- 
spondingly early.  This  generally  gives  the  patient  the  first  sug- 
gestion of  the  presence  of  a  cavity.  Often,  also,  the  dentist 
overlooks  these  decays  until  this  breakage  reveals  them.  This 
is  often  fatal  to  the  pulp  of  the  tooth,  especially  in  cases  in 
which  the  decay  has  begun  farther  to  the  gingival,  as  in  the  decay 
on  the  left,  in  Figure  110,  or  in  those  cases  in  which  the  enamel 
cap  is  unusually  strong,  as  in  Figure  111.  In  the  decay  seen  in 
the  right  of  Figure  110,  the  undermining  of  the  enamel  seems 
extreme.  This  is  often  the  case  in  those  decays  that  have  pene- 
trated the  enamel  as  a  small  opening  without  much  superficial 
spreading,  as  is  apparent  in  this  case.  In  Figure  109  there  is 
an  excellent  showing  of  backward  decay  of  enamel  in  the  decay 
seen  on  the  left  of  the  figure.  In  this  case  the  cut  is  to  one  side 
—  the  buccal  side  —  of  the  central  area  of  the  decay,  and  shows 
the  projection  of  the  decay  buccally,  along  the  dento-enamel 
junction,  its  progress  in  the  dentin  and  the  whitened  area  show- 
ing the  backward  decay  of  the  enamel.  Incidentally  this  cut 
has  been  in  the  line  of  the  projection  of  the  mesio-buccal  horn 
of  the  pulp,  which  is  unusually  long,  demonstrating  again  the 
clinical  necessity  of  avoiding  the  recessional  line  of  this  horn  of 
the  pulp  in  the  preparation  of  cavities,  both  proximal  and 
occlusal.  For  here  it  may  also  be  noticed  how  very  close  the 
small  occlusal  cavity  is  to  this  horn  of  the  pulp.    Finally,  it  is 


Fig.    112. 


FiQ.  112.  A  photograph  of  a  split  bicuspid  disclosing  three  beginning  decays  which  only  just 
reach  the  dento-enannel  junction.  Any  one  of  these  will  quickly  undermine  the  dento-enamel  junction 
if  neglected.  The  pit  decays,  if  allowed  to  become  deep,  often  undermine  the  enamel  of  the  proximal 
surfaces  also. 

Fig.  113.  A  beginning  decay  in  the  mesial  surface  of  a  small  three-cusped  molar,  in  which  solu- 
tion of  the  dentin  is  just  beginning.  A  very  characteristic  light-colored  hyaline  area  in  the  dentin  is 
fringed  with  deep  cloud.  The  decay  of  the  enamel  has  extended  considerably  toward  the  occlusal 
surface. 


13 


Fio.    114. 


Fig.  114.  The  photograph  in  this  ca.se  was  taken  with  the  surface  dry,  with  the  expectation  that 
the  areas  of  decay  would  show  whiter.  This  succeeded  well  with  the  decay  on  the  left  side,  but  not 
with  the  one  on  the  right.  The  hyaline  area  of  the  left  decay  is  well  shown.  The  extension  occlusally 
of  decay  along  the  dento-enamel  junction  and  the  very  white  backward  decay  of  the  enamel  are  inter- 
esting features.  After  this  photograph  was  made,  the  polished  surface  was  cemented  to  a  cover  glass 
and  ground  thin  for  photomicrographing,  and  Figures  115,  116  were  made. 

13a 


Fig.  115. 

Fig.   115.      Pliotomicrograph  showing  the  carious  area  seen  on  the  left  of  the  small  photograph, 
Figure  114.  d.    Dentin.  e.   Enamel.         x.   Area  of  decay.  y.    Line  of  actual   solution  of  the 

calcium  salts  of  the  dentin.  '/,.  Uackward  decay  of  the  enamel,  which  shows  very  white  by  reflected 
light,  but  is  dark  by  transmitted  light.  In  the  drying  of  the  specimen,  the  decayed  dentin  has 
shrunken  and  pulled  a  little  away  from  the  enamel.  A  slight  break  of  the  t-naTiiel  rods  has  occurred 
at  X,  and  a  little  confusion  of  the  decayed  rods  has  occurred  near  Ihe  letter  y.  No  enamel  rods  have 
fallen  out,   however,  and  niicrotirgnnisms  have  not  been   admitted   to   the  dentin. 


Fig.  IIG. 


Fig.   116.     Photomicrograph  of  the  decayed  area  on  the  right  side  in  Figure  114.  d.   Dentin. 

E.     Enamel.  x.     Area  of  decay.  z.     An  extension  of  the  superficial  beginning  of  decay  of  the 

enamel  occlusally.  The  dento-enaniel  junction  is  seen  between  d  and  e.  In  this  case  the  enamel  rods 
have  fallen  into  a  tangled  mass  in  the  deeper  portion  of  the  central  part  of  the  decay  at  X,  leaving 
a  partly  open  cavity  in  the  enamel.  Tlie  dentin  beneath  is  considerably  decayed  but  has  not  been 
pulled  away  from  the  enamel  by  shrinkage.  The  extension  of  the  decay,  as  seen  in  the  perpendicular 
section,  has  been  toward  the  occlusal  portion  of  the  tooth.  The  extension  of  beginning  on  the  surface 
seen  at  z  is  in  a  degree  separated  from  the  principal  area  of  decay  and  extends  toward  the  dento- 
enamel  junction  in  a  flamelike  tongue,  following  the  course  of  the  enamel  rods. 


.,  '^."'■.,''';  J'"?  excellent  photograph  of  a  split  bicuspid  with  Tuesial  and  distal  decavs  is  reniark- 
aDiy  similar  to  the  last,  but  m  many  ways  a  moie  perfect  picture  than  Figure  114.  In  the"  decay  on  the 
left,  the  enamel  rods  are  broken  down  and  are  lying  in  the  cayity  in  the  enamel  in  a  tangled  mass. 
in  tne  decay  on  the  right,  the  enamel  rods  are  still  in  perfect  position  and  no  microorganisms  have 
been  admitted  to  the  dentin.  The  dark  portion  of  the  dentin  accurately  exhibits  actual  decay  of  the 
dentin  m  both  decays.  The  hyaline  areas  are  both  very  well  shown.  "The  forked  projection  of  the 
flamellke   tongue   on    the   left,    formed   by   the  border   of   cloud,    is   one   of   the   singularly    interesting 


Mi 


Fig.  118.  Tho  halves  of  a  split  bicuspid  in  which  decay,  through  an  opening  Ihroiif^h  the  enamel 
that  has  remained  small,  has  involved  the  pulp  before  the  marginal  ridge  has  broken,  though  it  18 
extensively  iindenuined. 


CABIES  AS  A   WHOLE.      ITS   CLINICAL  FEATURES.  97 

well  to  notice  that  the  very  heavy  enamel  cap  shown  in  Figure 
111  has  been  no  bar  to  the  invasion  of  caries,  but  that,  on  the 
other  hand,  has  been  rather  a  menace  in  that  the  failure  to  break 
away  early  has  kept  the  cavity  hidden  and  maintained  condi- 
tions favorable  to  the  rapid  advance  of  caries  of  the  dentin. 

Occlusal  and  Pboximal  Surface  Decays  in  Bicuspids. 

ILLUSTRATIONS:    FIQORES  112-118. 

Principal  clinical  features  :  (1.)  In  pit  and  fissure  decays, 
the  danger  of  undermining  the  mesial  and  distal  marginal  ridges 
by  extension  of  caries  along  the  dento-enamel  junction,  involving 
also  the  enamel  of  the  proximal  surfaces.  (2.)  In  proximal  sur- 
face cavities  the  clinical  characters  are  the  same  as  in  proximal 
surfaces  of  the  molars. 

The  positions  in  which  pit  decays  occur  in  the  bicuspids 
are  well  shown  in  Figure  112.  The  occurrence  of  these,  inde- 
pendent of  caries  of  the  proximal  surfaces,  is  not  nearly  as 
frequent  as  in  the  molars,  yet  a  considerable  number  are  met 
with.  If  these  are  treated  before  considerable  progress  has  been 
made,  they  are  very  simple  cases ;  but,  as  decay  progresses,  it 
quickly  undermines  the  marginal  ridge  and  is  liable  to  weaken 
the  enamel  of  the  proximal  surface  to  such  an  extent  that  this 
must  be  cut  away  to  make  a  safe  treatment  by  filling.  In  the 
illustration,  Figure  112,  which  presents  decays  of  the  enamel  in 
each  pit  and  in  its  distal  surface,  it  will  be  noted  that,  as  these 
progress  in  the  dentin,  they  will  quickly  undermine  the  enamel 
of  both  the  marginal  ridge  and  the  proximal  surface,  and  the 
enamel  of  these  parts  will  be  weakened  by  backward  decay. 
This  undermining  often  makes  a  proximo-occlusal  filling  neces- 
sary even  though  there  may  have  been  no  proximal  decay. 

Many  of  the  proximal  decays  in  bicuspids  begin  near  the 
marginal  ridges,  as  in  the  molars.  This  is  illustrated  in  the 
beginning  of  decay  of  the  enamel  in  the  distal  surface  in  Figure 
112.  These  undermine  the  marginal  ridges  and  disclose  the  cavi- 
ties early  in  their  progress.  In  Figure  113  the  beginning  of  the 
decay  has  been  farther  toward  the  gingival,  and  spreading  on 
the  surface  of  the  enamel  toward  the  occlusal  has  occurred. 
This  is  seen  also  in  Figure  114  in  the  decay  on  the  right  side  of 
the  figure  and  is  much  more  plainly  seen  in  the  photomicrograph 
of  the  same  decayed  area  in  Figure  116.  The  excellent  photo- 
graph of  the  split  bicuspid  in  Figure  117,  shows  the  most  usual 
points  of  beginning  and  direction  of  progress  of  these  decays  to 

14 


98  PATHOLOGY    OP    THE    HARD    TISSUES    OF    THE    TEETH. 

great  advantage.  It  will  be  noticed  that  in  the  cavity  on  the  left 
side  of  Figure  117,  decay  has  already  begun  to  undermine  the 
enamel  forming  the  marginal  ridge,  and  the  distance  to  the  pulp 
is  so  great  that  the  breakage  of  the  marginal  ridge  would  prob- 
ably occur,  disclosing  the  presence  of  the  cavity  before  the  pulp 
would  become  involved.  But  this  tooth  shows  that  the  pulp  has 
receded  and  is  smaller  than  usual.  In  many  cases  the  pulp  is 
involved  before  the  breakage  of  the  marginal  ridge.  This  brings 
us  to  the  necessity  of  discovering  these  decays  at  an  early  date 
in  their  progress  in  order  to  limit  the  injury  to  the  dentin  by 
caries  and  prevent  the  exposure  of  the  pulp.  In  the  split 
bicuspid,  Figure  118,  there  is  a  mesial  cavity  which  has  extended 
in  the  dentin  to  the  exposure  of  the  pulp  before  the  mesial  mar- 
ginal ridge  is  broken.  This  shows  well  the  extension  along  the 
dento-enamel  junction  under  the  occlusal  surface  of  the  tooth. 
This  great  extension  along  the  dento-enamel  junction  and  the 
general  form  of  the  cavity  is  typical  of  this  class  of  cases  in 
which  the  opening  of  the  cavity  remains  closely  covered  by  the 
l^roximating  tooth. 

Taken  all  together,  the  principal  clinical  differences  between 
the  proximal  decays  of  the  bicuspids  and  the  molars  are  to  be 
found  in  the  smaller  comparative  size  of  the  bicuspid  in  relation 
to  the  exposure  of  surface  to  the  beginnings  of  decay.  For  this 
reason,  the  amount  of  sound  tissue  in  proportion  to  carious  tissue 
quickly  becomes  much  less  than  in  the  molar  teeth,  and  their  suc- 
cessful treatment  is  for  this  reason  rendered  more  difficult. 
These  facts  intensify  the  demand  that  closer  examinations  be 
made  and  filling  resorted  to  earlier  in  the  progress  of  caries  in 
the  bicuspids.  If  this  will  not  allow  the  cutting  to  be  made  much 
narrower  on  the  surface,  it  can  be  made  much  shallower,  giving 
proportionally  a  much  greater  mass  of  healthy  tissue  to  support 
fillings  and  to  limit  the  danger  of  breakage. 

The  photograph  from  a  split  bicuspid.  Figure  114,  shows  a 
cavity  in  the  mesial,  and  also  one  in  the  distal  surface  and  is  of 
especial  interest.  The  forms  are  fairly  well  outlined,  showing 
particularly  in  the  one  on  the  left  of  the  picture,  that  the  enamel 
rods  have  not  fallen  out.  Yet  the  clouding  of  the  dentin  reaches 
to  the  pulp  chamber.  The  acid,  which  has  percolated  through 
the  decaying  enamel,  has  begun  dissolving  away  the  calcium  salts 
of  the  dentin.  This  extends  along  the  dento-enamel  junction, 
both  to  the  occlusal  and  to  the  gingival.  In  this  picture  the 
backward  decay  of  the  enamel,  in  the  extension  toward  the 
occlusal,  is  particularly  well  shown.    It  is  this  backward  decay 


CARIES    AS   A    WHOLE.       ITS    CLINICAL   FEATURES.  99 

of  the  enamel  which  so  weakens  it  that  it  often  breaks  away 
early  in  the  progress  of  the  decay.  The  decay  in  the  mesial  sui'- 
face,  or  right-hand  side  of  the  picture,  has  not  been  well  shown 
by  the  engraver,  but  in  this,  in  the  central  area  of  the  decay  in 
the  enamel,  the  enamel  rods  are  broken  down  and  lie  in  a  tangled 
mass  near  the  dento-enamel  junction. 

After  the  photograph  of  this  tooth  was  made,  the  cut  sur- 
face was  cemented  to  a  cover-glass,  and  this  in  turn  to  a 
grinding-disk,  which  was  placed  in  the  grinding  machine,  and 
a  section  ground  thin  enough  for  microscopic  examination  by 
transmitted  light.  From  this,  photomicrographs  were  made 
which  show  the  carious  areas  in  greater  detail.  The  sides  to 
which  each  belong  have  been  preserved  as  they  appear  in  the 
small  photograph. 

If  the  decay  on  the  left  in  the  photomicrograph,  Figure  115, 
is  studied,  the  amount  of  the  solution  of  lime  salts  from  the 
dentin,  as  it  is  shown  at  y,  is  easily  followed.  The  injury  to  the 
dentin,  however,  extends  from  the  point  of  the  dentin  cusp  near 
the  occlusal,  down  past  the  decay  of  the  enamel  toward  the  gingi- 
val. At  z  the  outline  of  the  backward  decay  of  the  enamel,  seen 
in  the  small  photograph,  is  quite  plainly  shown,  but  by  trans- 
mitted light  it  is  dark.  A  backward  decay  toward  the  gingival 
is  not  so  well  shown,  because  of  some  little  cracking  of  the  enamel 
in  that  region,  which  mars  the  picture.  The  occlusal  portion  of 
this  picture  is  upward,  as  it  is  in  all  of  the  photomicrographs. 

The  decay  on  the  right  of  the  small  picture.  Figure  114,  is 
represented  in  Figure  116.  Although  this  decay  has  not  caused 
enough  solution  of  calcium  salts  in  the  dentin  to  show  shrinkage 
in  drying,  the  injury  to  the  dentin  seems  to  be  considerable.  The 
enamel  rods  are  broken  down  in  the  central  area,  which  occurred, 
I  am  persuaded,  in  the  process  of  grinding,  for  my  notes  say 
that  the  surface  of  the  enamel  showed  no  loss  of  enamel  rods. 
The  grinding  of  the  surface  from  which  the  small  photograph 
was  made,  was  without  any  protection  by  cementing  the  enamel 
rods  together  by  solutions  of  balsam  or  shellac  to  prevent  move- 
ment, and  some  distortion  of  the  enamel  rods  on  the  superficial 
portion  of  the  cut  surface  would  easily  be  overlooked.  It  will  be 
seen  in  the  photomicrograph  that  many  of  the  partially  dissolved 
enamel  rods  lie  in  a  tangled  mass  in  the  deeper  parts  of  the 
cavity.  The  very  unusual  extension  of  the  carious  process  in  the 
enamel  toward  the  occlusal  at  z  will  also  be  noticed  here,  sepa- 
rated partially  from  the  principal  area  of  decay,  a  flamelike 
tongue  shoots  inward  from  the  surface  and  is  making  progress, 


100  PATHOLOGY   OP   THE   HAKD   TISSUES  OF   THE   TEETH. 

following  directly  the  length  of  the  enamel  rods.  This  represents 
a  new  decay  of  enamel  in  the  form  of  an  extension,  but  begin- 
ning upon  the  surface.  It  is  not  a  lateral  extension  within  the 
tissue,  but  marks  the  spreading  of  microorganisms  on  its  surface. 
It  is  well  to  note  particularly  the  direction  of  the  enamel  rods 
along  the  occlusal  side  of  the  flamelike  tongue  of  decay  shooting 
down  from  z,  with  reference  to  the  inclination  of  the  enamel 
wall  that  would  be  required  if  this  were  prepared  as  a  simple 
proximal  cavity.  It  will  be  seen  that  this  inclination  of  the 
enamel  rods  is  too  great  to  fill  against  safely,  for  it  is  in  such 
a  position  that  the  thinness  of  the  margin  of  the  filling  material 
would  be  insufficient  to  give  it  the  necessary  strength. 


MISPLACEMENT    OF    BEGINNING   PROXIMAL   DECAYS. 
ILLUSTRATIONS:    FIGURES  119,  120. 

It  has  been  noted,  in  considering  Figure  92,  that  the  proxi- 
mal decay  upon  the  mesial  of  the  bicuspid  is  out  of  the  ordinary 
position  to  the  lingual,  passing  partially  around  the  lingual 
angle  of  the  tooth.  Such  displacements  from  the  normal  position 
occur  frequently  on  account  of  irregularity  of  the  teeth  bringing 
their  surfaces  together  in  unusual  relations  to  each  other,  or 
some  such  accidental  condition. 

In  Figure  119  a  peculiar  shaped  cavity  is  presented  in  the 
mesial  surface  of  the  central  incisor,  having  a  prolongation 
running  labio-incisally.  "When  the  tooth  is  seen  standing  alone, 
such  form  of  beginning  decay  might  seem  difficult  to  explain, 
but  examination  of  Figure  120  explains  the  reason  for  this  unus- 
ual form.  The  relative  position  of  the  two  teeth  is  such  as  to 
bring  very  near  contact  directly  along  the  line  which  this  decay 
has  taken  in  the  enamel,  and  is  the  local  influence  which  has 
caused  this  peculiarity.  In  any  case,  if  a  tooth,  a  bicuspid  for 
instance,  is  turned  one  quarter  around  upon  its  axis,  so  that  the 
buccal  surface,  proper,  becomes  the  mesial  surface,  and  the 
lingual  surface,  proper,  becomes  the  distal  surface,  decay,  if  it 
occurs,  will  start  in  the  portion  of  the  enamel  that  is  in  near 
contact  with  the  neighboring  tooth. 

Therefore,  we  see  again  in  this  that  the  nature  or  perfection 
of  the  enamel  is  in  no  wise  an  element  in  the  localization  of  decay 
on  the  smooth  surfaces  of  the  teeth.  These  unusual  forms,  and 
apparently  unusual  positions,  of  beginning  caries  are  always 
traceable  to  some  condition  that  serves  to  invite  lodgment  and 


Fig.  119. 


Fia.  120. 


Fias.  119,  120.  Drawings  showing  an  unusual  form  of  decay  in  a  central  incisor  in  Figure  119, 
and  the  overlapping  of  the  two  central  incisors  in  Figure  120,  in  such  a  way  as  to  bring  the  sur- 
faces of  the  teeth  in  very  near  approach  in  such  a  direction  as  to  produce  this  form  of  beginning 

14b 


Fig.  121. 


Fig.  121.  A  photomicrograph  ot  .in  extensive  decay  o(  the  enamel  on  tlie  proximal  surface  of  a 
molar.  d.  Dentin.  E.  Enamel.  x.  Area  of  deca.y  of  enamel.  Y.  An  extension  of  the  super- 
ficial beginning  of  caries  gingivall.v  furtlier  than  the  illustration  shows.  No  enamel  rods  have  fallen 
out.  The  enamel  is  decayed  through  to  the  dento-enamel  junction  and  some  solution  of  the  dentin  has 
been  begim  by  the  percolation  of  acid  through  the  decayed  enamel.  The  extension  of  caries  of  enamel 
gingivally  is  characteristic  of  lodgments  of  food  between  the  teeth  and  absorption  of  the  inter- 
proximal gum  tissue. 


Fig.  122.  A  photomicrograph  of  caries  of  the  enamel  on  (he  proximal  surface  of  a  molar,  with 
an  extension  gingivally.  The  decay  from  the  original  point  of  beginning  has  penetrated  the  enamel 
almost  to  the  dento-enamel  junction.  The  extension  gingivally  Is  partially  separated  from  the  prin- 
cipal decay.     See  Figure  123. 


Fig.  123. 


Fia.  123.  Another  photomicrograph  from  the  decay  shown  in  Figure  122,  made  with  less  ampli- 
fication in  order  to  show  the  relation  of  the  decay  to  the  pulp  chamber  and  other  parts  of  the  tooth. 
It  includes  a  little  less  than  one-haU  of  the  mesio-distal  section  of  the  crown.  In  the  preparation  of 
a  cavity  for  filling  in  such  a  case,  it  would  be  an  error  to  cut  the  gingival  wall  at  d.  The  true  cavity 
lines  would  place  the  gingival  wall  at  the  line  c  ;  the  axial  wall  on  the  line  b  ;  the  occlusal  wall  of 
the  step  on  the  line  a. 


GABIES  AS  A   WHOLE.      ITS   CLINICAL   FEATUEES.  101 

to  protect  colonies  of  microorganisms.  In  the  examination  of 
many  teeth,  such  unusual  positions  of  beginning  decay  are  not 
very  rare. 

SECONDARY  EXTENSIONS   GINGIVALLY   OF   PROXIMAL  DECAYS. 
ILLUSTRATIONS:    FIGURES  121,  122,  123. 

In  proximal  surfaces  another  condition  arises  frequently 
that  deserves  especial  attention  on  account  of  its  great  clinical 
importance.  Figure  121  shows  a  large  carious  area  of  enamel 
at  X  that  has  just  passed  through  the  enamel  and  begun  the  solu- 
tion of  the  calcium  salts  of  the  dentin.  In  this  case,  a  secondary 
beginning  of  caries  of  the  enamel  has  occurred  toward  the  gingi- 
val at  Y,  running  farther  gingivally  than  the  illustration  shows. 
This  occurs  in  somewhat  less  breadth  in  a  considerable  number 
of  cases  on  account  of  lodgment  and  retention  of  food  between 
the  teeth.  Because  of  roughening  of  the  surfaces,  by  the  swelling 
of  the  decayed  area,  or  because  of  the  falling  away  of  enamel 
rods  in  one  or  'both  of  the  proximating  teeth,  the  food,  instead 
of  gliding  out  laterally  in  the  normal  way,  will  be  held,  and  will 
be  forced  more  and  more  onto  the  gum  tissue  as  other  food  is 
forced  in  upon  it.  In  this  way  the  interproximal  gum  tissue  will 
be  absorbed  and  a  pocket  will  be  formed  between  the  teeth  that 
will  be  well  enclosed  by  the  festoons  of  the  gum  to  the  buccal 
and  lingual,  and  by  coverings  of  debris  from  washings  by  the 
saliva.  Acid  fermentation  will  become  established  in  this  pocket. 
The  acid  formed  by  this  fermentation  will  be  in  contact  with  the 
surface  of  the  enamel  and  its  calcium  salts  will  be  dissolved. 
Another  case  of  similar  character  is  illustrated  in  Figure  122. 
The  progress  toward  the  gingival  line  is  less  extensive,  but  in 
depth  its  progress  is  more  pronounced  and  it  has  a  more  evident 
separation  from  the  original  beginning  point  of  decay  in  this 
surface.  As  in  most  of  the  decays  of  enamel  at  this  stage,  the 
swelling  of  the  carious  enamel  is  very  apparent  in  the  principal 
decayed  area.  There  seems  to  be  some  effect  upon  the  partially 
dissolved  enamel  rods  that  causes  them  to  lengthen  slightlj', 
causing  this  swollen  appearance.  Further,  when  these  rods  are 
disturbed,  they  often  collapse  into  a  tangled  mass  in  which  they 
seem  bent  and  twisted  together  in  such  a  way  as  to  suggest  that 
they  have  become  softened  and  in  a  degree  pliable.  See  Figure 
116.  This  swelling  appears  in  a  number  of  the  photomicro- 
graphs. I  do  not  remember  that  any  other  writer  has  mentioned 
it.    In  the  hand  grinding  that  I  had  done  before  this  had  not  been 


102  PATHOLOGY   OF    THE    HAKD    TISSUES    OF    THE    TEETH. 

noticed,  but  in  many  of  my  recent  grindings  with  the  machine, 
in  which  the  final  thinning  down  of  the  specimen  is  done,  with 
all  such  frail  parts  held  together  in  hard  balsam  or  shellac,  it 
has  become  too  prominent  to  be  overlooked.  Indeed,  in  the 
grinding  by  the  machine,  the  preparation  is  more  delicately 
done  than  heretofore  and  much  carious  tissue  is  saved  in  form 
that  formerly  was  lost.  This  is  giving  a  closer  insight  into  the 
actual  conditions  existing  in  the  beginnings  of  caries  of  enamel. 
The  roughening  of  the  surface  of  the  decayed  area  is  evidently 
a  factor  in  the  holding  of  food  and  the  establishment  of  a  pocket 
between  the  teeth.  This  is  aided  later  by  the  falling  out  of  the 
enamel  rods  and  the  more  general  roughening  of  the  surface  on 
that  account. 

Those  conditions,  which  cause  the  food  to  lodge,  become 
a  cause  of  the  wide  secondary  extension  of  the  carious  area 
toward  the  gingival  line,  which  creates  a  very  ugly  clinical  con- 
dition, and  one  that  is  too  often  overlooked  at  a  time  when  it 
might  be  easily  remedied.  During  the  preparation  of  the  cavity, 
such  an  extension  of  decay  as  is  shown  in  Figures  121,  122,  will 
show  a  white  line  of  more  or  less  thickness  on  the  cavo-surface 
angle  of  the  gingival  wall,  while  the  remainder  of  the  enamel 
wall  will  be  hard  and  firm.  This  is  further  illustrated  in  Figure 
123,  another  photomicrograph  from  the  same  specimen  as  that 
in  Figure  122,  but  made  with  less  amplification  in  order  that 
more  of  the  relation  of  the  carious  areas  to  the  tooth  and  its  pulp 
chamber  may  be  shown  on  the  ordinary  book  page.  In  this  case, 
if  the  occlusal  portion  of  this  proximal  decay  had  extended  into 
the  dentin  and  the  cavity  had  been  discovered  by  the  breaking 
away  of  the  enamel  at  a  time  when  the  secondary  extension  of 
decay  gingivally,  as  shown,  was  at  its  present  stage,  which  often 
occurs,  it  would  have  been  easy  to  overlook  this  extension  and 
prepare  the  cavity  with  its  gingival  wall  cut  at  the  line  d,  instead 
of  cutting  the  cavity  to  the  line  c.  Such  an  error  as  cutting  the 
gingival  wall  at  d  would  inevitably  have  resulted  in  disaster 
within  a  short  time.  In  practice,  the  only  way  in  which  to  make 
a  filling  that  will  not  soon  be  undermined  at  the  gingival  wall  is 
to  continue  the  extension  until  all  appearance  of  this  secondary 
caries  of  the  enamel  has  been  removed.  The  perfect  enamel  will 
then  show  the  usual  solid  vitreous  appearance  at  the  cavo-surface 
angle  of  the  gingival  wall.  Then  the  contact  point  must  be  so 
formed  and  the  filling  so  finished  as  to  later  on  prevent  the 
leakage  of  food  into  the  interproximal  space.  Afterward,  the 
regrowth  of  the  interproximal  gum  tissue  should  be  encouraged 


CARIES   AS   A   WHOLE.      ITS   CLINICAL   FEATUEES.  103 

by  local  stimulants  and  the  case  kept  under  observation  in.  the 
effort  to  have  it  refill  the  interproximal  space. 

Any  condition  which  allows  food  to  leak  into  the  interproxi- 
mal space,  be  held  and  forced  onto  the  gum  tissue,  will  cause  the 
absorption  of  the  gum  tissue  and  result  in  the  formation  of  a 
pocket.  In  time,  one  of  two  things  is  certain  to  happen :  (1)  acid 
fermentation  will  become  established  in  the  pocket  and  decay 
will  occur  farther  toward  the  gingival  line,  or  (2)  putrefactive 
decomposition  will  become  established,  and  finally  disease  of 
the  peridental  membrane  will  result.  Careful  clinical  study  has 
shown  conclusively  that  much  the  greater  number  of  the  decays 
met  with  in  practice  that  extend  far  toward  the  gingival  line,  or 
past  it  into  the  cementum,  have  occurred  in  this  way.  It  is  true, 
however,  that  a  considerable  proportion  of  these  have  occurred 
in  what  may  be  called  the  more  normal  way  by  the  spread  of 
decay  along  the  dento-enamel  junction  and  backward  decay  of 
the  enamel.  This  later  can  occur  only  in  the  badly  neglected 
cases. 

The  crowding  of  food  between  the  teeth  after  the  placing 
of  so-called  contour  fillings  in  the  earlier  days  of  cohesive  gold 
work  was  the  cause  of  widespread  loss  of  fillings  by  under- 
mining by  decay  at  the  gingival  margin.  The  former  employ- 
ment of  the  separating  file  as  it  had  been  developed  in  the  use 
of  non-cohesive  gold  was  continued  for  the  finishing  of  cohesive 
gold  fillings.  Flat  contacts  were  made  and  the  forms  of  proxi- 
mal surfaces  were  left  otherwise  in  imperfect  form.  There  had 
not  been  that  close  study  of  tooth  forms  which  enabled  men  to 
copy  them  with  accuracy,  or  to  appreciate  the  correctness  of 
forms  of  interproximal  contacts ;  neither  did  they  have  suitable 
instruments.  It  is  only  by  the  complete  relegation  of  the  sepa- 
rating file  to  past  history,  the  study  of  the  best  natural  forms 
of  interproximal  contacts  and  their  function  in  the  protection 
of  the  interproximal  spaces,  the  copying  of  these  in  the  shaping 
of  proximal  surfaces  of  fillings,  which  are  made  to  restore  the 
full  mesio-distal  breadth  of  the  teeth,  that  this  difSculty  in  the 
treatment  of  caries  of  proximal  surfaces  is  being  overcome. 
Decays  recurring  from  these  causes  are  especially  difficult  of 
treatment,  often  requiring  the  removal  of  a  filling  previously 
made,  in  order  to  reach  them  from  the  occlusal  surface.  They 
are  also  complicated  with  great  difficulties  in  getting  the  rubber 
dam  far  enough  to  the  gingival  to  protect  them  from  moisture. 

Therefore,  in  practice,  a  complaint  of  pain  being  produced 
by  food  lodgments,  or  of  food  being  held  between  the  teeth  in 


104  PATHOLOGY   OF   THE   HAED   TISSUES   OP   THE   TEETH. 

the  chewing  of  meats  or  other  stringy  foods,  should  receive 
immediate  attention,  the  cause  found  and  the  condition  remedied. 
It  may  occur  from  a  number  of  causes  besides  the  beginning  of 
caries,  and  will  occasionally  be  found  in  one,  two  or  more  teeth, 
in  mouths  in  which  no  caries  has  previously  occurred.  The 
proximal  contacts  may  be  bad  from  faulty  forms  of  the  teeth 
themselves,  they  may  have  become  bad  from  movements  of  the 
teeth  after  extractions,  the  contacts  may  have  become  flattened 
by  interproximal  wear,  but  oftenest  of  all,  they  have  become 
bad  because  of  beginning  of  proximal  decay.  I  may  say  that, 
personally,  I  have  done  no  other  thing  for  my  patients  that  has 
elicited  keener  expressions  of  appreciation  than  the  correction 
of  this  class  of  evils.  If  the  dentists  of  this  country  would  unite 
in  looking  closely  after  these  conditions  and  be  careful  in  their 
correction,  it  would  add  greatly  to  the  comfort  and  welfare  of 
their  communities,  save  thousands  of  teeth  for  useful  service 
and  enhance  the  usefulness  of  dentistry. 

INJURIES   BY   INTERPEOXIMAL   WEAR. 
ILLUSTRATIONS:  FIGURES  124128. 

The  clinical  consideration  of  caries  of  the  proximal  sur- 
faces of  the  bicuspids  and  molars  should  not  be  passed  without 
more  special  mention  of  the  injuries  that  result  from  interproxi- 
mal wear  and  the  flattening  of  the  contact  points  from  this  cause ; 
though  it  will  be  again  presented  from  the  technical  view  in  the 
second  volume.  The  general  principles  governing  the  lodgment 
of  food  debris  between  the  teeth  have  been  given  under  the  last 
heading,  to  which  the  reader  is  referred,  in  which  interproximal 
wear  of  the  contact  points  was  mentioned  as  one  of  the  causes. 

A  certain  indefinite  amount  of  wear  of  the  mutual  points 
of  proximal  contact  between  the  teeth  as  they  stand  in  the  arch, 
must  be  regarded  as  normal.  Almost  any  tooth  extracted  after 
the  age  of  twenty-five  or  thirty  years  will  show  a  facet  of  wear 
on  its  point  of  contact  with  its  fellow.  A  number  of  measure- 
ments of  these  give  an  average  of  a  loss  of  about  one  centimeter 
in  the  length  of  the  arch  from  this  cause  when  measured  on  the 
labial  and  buccal  surfaces  of  the  teeth  around  the  arch  from 
the  mesio-buccal  cusp  of  one  third  molar  to  the  other  at  the  age 
of  forty  years.  This  wear  increases  as  the  person  grows  older. 
When  this  wear  is  fairly  even  in  its  distribution  among  the 
several  teeth,  it  can  not  be  regarded  as  abnormal,  nor  is  it  a 
cause  of  material  injury.    Such  wear  does  not  loosen  the  normal 


Fig.  124. 


Figs.  124-128.  This  group  of  five  teeth,  all  of  which  were  extracted  by  the  author  because  of 
neglected  disease  of  the  peridental  tneiiibranes.  caused  by  tlie  crowding  of  food  between  the  proximal 
surfaces,  flattened  by  inlcrproxinial  wear.  These  should  have  been  protected  at  the  proper  time  by 
building  prominent  contacts  for  the  cure  of  the  ditticulty.  Figures  l'^7,  128,  illustrate  the  position  in 
wliich  decay   most    usually   occurs   in    these   cases. 


CABIES   AS  A   WHOLE.      ITS   CLINICAL   FEATURES.  105 

pressure  of  the  contact  of  tooth  with  tooth  as  they  stand  in  the 
arch  in  any  degree.  In  the  balance  of  forces  which  confine  the 
teeth  in  normal  form  and  occlusion  in  the  arch,  there  is  a  mod- 
erate but  continuous  pressure  exerted  to  hold  them  firmly  one 
against  the  other,  which,  when  conditions  remain  normal,  con- 
tinues through  life.  This  is  much  more  than  sufficient  to  take 
up  any  loss  of  length  of  the  arch  around  its  curve  that  may  be 
occasioned  by  the  wear  of  the  contact  points.  This  is  often 
shown  by  the  quickness  with  which  the  teeth  anywhere  in  the 
arch  will  close  together  when  a  contact  point  has  been  lost  by 
reason  of  caries  or  the  reduction  of  an  intervening  space  where 
a  tooth  has  been  removed.  This  wear  is  produced  by  the  slight 
movement  of  the  teeth  in  their  alveoli  allowed  by  the  peridental 
membrane.  It  is  not  equal  in  all  parts  of  the  mouth,  but  is 
greatest  among  those  teeth  which  do  the  heavier  work  in  chewing 
food,  especially  the  second  bicuspid  and  the  first  and  second 
molars.  In  these  teeth  it  is  frequently  excessive.  The  five  first 
molars,  photographs  of  which  illustrate  this  subject,  were  each 
removed  by  the  author  because  of  injury  done  to  their  peridental 
membranes  by  the  food  which  was  held  by  the  flattened  sur- 
faces and  crowded  against  the  interproximal  gum  tissue.  The 
flat  facets  shown  in  the  photographs  exhibit  the  amount  of 
interproximal  wear  that  may  be  expected  to  occur  frequently  in 
persons  fifty  to  sixty  years  old,  who  have  made  good  use  of  their 
teeth.  Many  cases  may  be  observed  that  have  become  worn  as 
much  as  these,  or  nearly  so,  in  which  no  special  harm  has 
resulted,  and  they  require  no  attention.  But  in  a  certain  number 
of  these,  food  that  is  unusually  tough  and  stringy  will  some 
time  be  forced  between  the  teeth  and  not  be  removed.  At  sub- 
sequent meals  more  will  be  forced  in,  until  finally  the  pressure 
of  the  contact  will  be  loosened  and  remain  so.  Then  trouble 
has  begun  in  earnest,  which,  if  not  relieved  promptly,  will  cer- 
tainly result  in  disaster.  Within  my  personal  observation, 
certain  persons  have  manifested  a  remarkable  unconcern  as  to 
this  condition,  claiming  that  they  had  never  experienced  any 
uneasiness  whatever,  even  when  large  amounts  of  gum  tissue 
had  been  destroyed  by  the  pressure  of  food  debris.  Such  cases 
are  often  hopeless  when  first  seen.  But  when  the  dentist  dis- 
covers such  cases  in  time  to  act  successfully,  he  should  express 
the  necessity  for  treatment  by  proceeding  at  once  to  do  that  which 
is  necessary.  Such  a  course  will  save  his  patient  from  the  loss 
of  the  teeth  concerned.  Others,  and  much  the  greater  number, 
are  in  constant  trouble  from  the  beginning  of  the  lodgments 


106  PATHOLOGY   OP   THE   HARD   TISSUES   OF   THE   TEETH. 

and  gladly  accept  anything  that  promises  relief.    The  number  of 
persons  who  have  complained  that  they  have  been  unable  to 
obtain  relief  when  applying  to  their  dentist  indicates  that  the 
body  of  the  profession  have  been  slow  to  realize  the  necessity 
for  treatment,  or  to  see  the  way  to  make  it  successful.    As  said 
in  the  previous  article,  one  of  two  things  is  sure  to  result  if 
this  continues:     (1)  acid  fermentation  will  become  established 
in  the  pocket  formed  between  the  teeth  as  a  result  of  the  absorp- 
tion of  the  interproximal  gum  tissue,  by  the  pressure  of  the 
accumulations,  and  caries  beginning  near  the  gingival  line,  as 
shown  in  Figures  127,  128,  will  result;    or   (2),  putrefactive 
decomposition  will  occur,  resulting  in  disease  of  the  peridental 
membrane.    In  Figure  124  a  considerable  absorption  is  shown 
on  the  side  of  the  mesial  root  of  the  lower  molar,  which  seems 
to  have  been  caused  by  the  continued  irritation  of  the  peridental 
membrane,  a  thing  that  has  been  observed  in  a  considerable 
number  of  such  cases.    The  common  habit  of  dentists  of  throw- 
ing extracted  teeth  into  the  waste-basket  or  elsewhere  without 
examination  of  the  condition  of  their  roots,  is  accountable  for 
the  slowness  of  the  development  of  our  knowledge  of  the  effect 
of  pathological  conditions  upon  the  peridental  membranes  and 
the  hard  tissues  which  they  invest.    In  this  illustration,  Figure 
124,  the  surface  flattened  by  wear  is  very  broad.    In  Figure  125 
the  enamel  has  been  worn  entirely  through,  exposing  the  dentin. 
In  Figure  126  a  decay  of  the  enamel  had  begun  near  the  contact 
point  but  had  ceased  to  progress  because  of  some  favorable 
change  of  conditions.    This  has  become  blackened  and  the  facet 
of  wear  has  later  spread  over  it.    The  location  of  the  decays  that 
have  begun  in  Figures  127,  128,  is  typical  of  the  beginnings  of 
decay  in  these  conditions  and  speak  for  themselves  as  to  the 
difficulty  of  treatment.    From  every  point  of  view  cases  of  this 
class  call  for  immediate,  careful  consideration  and  treatment 
in  the  very  early  stages  of  their  progress,  or  just  so  soon  as  it 
is  noticed  that  there  is  trouble  that  seems  to  persist.    Only  one 
thing  promises  relief,  and,  fortunately,  has  proven  very  effective 
when  carefully  done.    This  is  to  cut  a  cavity  in  one  of  the  worn 
teeth  that  shall  fully  include  the  worn  area,  make  a  good  and 
sufficient  separation  of  the  teeth   and  build  out  a  prominent 
contact  that  will  hold  the  surfaces  sufficiently  apart  and  prevent 
further  leakage  of  food  into  the  interproximal  space.    This  treat- 
ment is  given  in  detail  in  the  volume  on  technical  procedures  in 
filling  teeth. 


Fig.  129. 


Fio.  129.  A  blackMied  spot  on  the  mesial  surface  of  a  central  incisor  caused  by  a  beginning 
decay  of  the  enanicl.  which  was  stopped  by  a  change  of  conditions,  and  afterward  became  very  dark. 
It  shows  the  most  common  position  of  beginning  of  decay  in  these  surfaces. 

Fio.  130.  An  open  cavity  in  the  mesial  surface  of  a  central  incisor  with  a  superficial  extension 
of  decay  nmning  away  from  it,  toward  the  linguo-gingival  angle  of  the  surface.  A  similar  superficial 
whitening  leads  away   to  tlie  labio-gingival  angle,   which  was  lost  in  Ihc  high  light  in  photographing. 


caeies  as  a  whole.     its  clinical  features.  107 

Proximal  Surface  Decays  in  Incisors  and  Cuspids. 

ILLUSTRATIONS:    FIGURES  78-81,  129-133. 

Principal  clinical  features:  (1.)  The  V-sliaped  form  of 
the  proximal  surfaces.  (2.)  The  necessity  that  cavities  be 
approached  through  the  labial  or  lingual  embrasures,  differing 
from  the  approach  through  the  occlusal  surface  in  the  molars  and 
bicuspids.  (3.)  The  curvature  of  the  surface  at  the  usual  jwint 
of  initial  attack  carries  extensions  of  decay  along  the  dento- 
enamel  junction  quickly  to  the  undermining  of  the  lingual  or 
labial  enamel  plates,  or  often  both.  (4.)  The  frequent  danger 
of  the  spread  of  decay  incisally  along  the  dento-enamel  junc- 
tion, destroying  the  support  of  the  incisal  angle.  (5.)  The  ten- 
dency to  spreading  of  caries  to  the  linguo-gingival  and  labio- 
gingival  angles  of  the  surface,  especially  after  fillings  have  been 
made.  (6.)  The  triangular  forms  of  prepared  cavities,  with 
extensions  at  the  labio-gingival  and  linguo-gingival  angles  only, 
instead  of  the  square-cut  cavities  in  proximal  surfaces  of  the 
bicuspids  and  molars.  (7.)  The  necessity  for  forming  incisal 
anchorages  of  a  form  not  used  elsewhere.  (8.)  The  greater 
necessity  for  esthetic  considerations  in  all  parts  of  the  treatment, 
and  especially  in  the  preservation  of  the  stronger  parts  of  under- 
mined labial  enamel.  (9.)  The  great  danger  of  injury  to  the 
attachment  of  the  soft  tissues  to  the  tooth  at  the  crest  of  the 
arch  of  the  gingival  line  on  the  mesial  and  distal  surfaces  in 
the  use  of  ligatures. 

The  two  groups  of  Figures,  78-81,  129-133,  taken  together, 
present  a  progression  from  the  very  early  beginnings  of  caries 
in  the  enamel  in  proximal  surfaces  of  incisors  and  cuspids  to  a 
very  considerable  invasion  of  the  dentin.  They  give  a  fair  view 
of  the  usual  conditions  found,  including  the  place  of  beginning 
and  the  manner  and  direction  of  the  invasion.  Particular  atten- 
tion should  be  given  to  the  arch  of  the  gingival  line  as  it  passes 
from  labial  to  lingual  across  the  proximal  surfaces.  This  is 
well  shown  in  Figures  129,  130,  which  exhibit  plainly  the  danger 
of  serious  damage  to  the  attachment  of  the  soft  tissue  to  the 
tooth  at  the  crest  of  the  arch  of  the  gingival  line  by  tying  liga- 
tures tightly  and  forcing  them  to  the  gingival  line  on  the  labial 
and  lingual  surfaces.  This  danger  is  found  particularly  with 
the  incisors  and  cuspids,  and  great  damage  is  frequently  done 
by  inattention  to  this  point. 


108  PATHOLOGY    OF    THE    HAED    TISSUES    OF    THE   TEETH. 

Figure  129  shows  particularly  well  the  most  common  posi- 
tion of  the  beginning  caries  on  the  mesial  surfaces  of  the  incis- 
ors. It  is  sometimes  a  little  closer  to  the  incisal  angle  and 
sometimes  a  little  farther  away,  though  it  does  not  often  vary 
very  much  from  the  point  shown.  The  spot  shown  is  a  begin- 
ning decay  which  had  penetrated  the  enamel  but  little  appar- 
ently, and,  having  been  stopped  by  a  change  of  conditions, 
became  very  dark.  Figure  130  was  intended  to  show  the  broad 
spreading  of  caries  which  sometimes  occurs  on  the  proximal 
surfaces  of  these  teeth.  This  is  plainly  shown  on  the  lingual  in 
the  rounded  tongue  of  superficial  decay  extending  away  from  the 
dark,  open  cavity  toward  the  linguo-gingival  angle  of  the  sur- 
face. A  somewhat  similar  extension  toward  the  labio-gingival 
angle  was  apparent,  but  the  high  light  in  the  photograph  has 
hidden  that  point.  Such  extensions  as  that  seen  upon  the  lingual 
in  this  photograph  are  particularly  liable  to  occur  in  very  sus- 
ceptible persons  after  fillings  have  been  made,  unless  extensions 
of  the  angles  of  cavities  have  been  made  to  include  the  area  of 
danger.  Otherwise,  this  case  presents  a  wide-open  cavity  in 
which  the  imdermined  enamel  has  broken  away  most  toward  the 
lingual  surface.  The  penetration  of  dentin  and  its  direction  of 
progress  is  progressively  shown  in  Figures  131,  132,  133.  In 
the  first  of  these,  the  enamel  rods  have  fallen  out,  and  the  spread- 
ing of  decay  along  the  dento-enamel  junction  is  in  progress. 
The  faint  hyaline  zone  is  seen  reaching  almost  to  the  pulp  cham- 
ber. This  decay  is  rather  nearer  the  gingival  line  than  iisual, 
because  the  strong  rounding  of  the  distal  surface  inciso-gingivally 
placed  the  contact  point  unusually  far  from  the  incisal.  We  see 
in  this  that  the  form  of  the  particular  tooth  plays  its  role  in  the 
particular  locality  of  the  point  of  attack  in  the  enamel  by  caries. 
The  next  photograph,  showing  decay  in  the  mesial  surface  of  a 
cuspid,  Figure  132,  gives  a  false  impression  in  that  it  shows  the 
enamel  rods  in  position,  while,  in  fact,  the  cut  is  slightly  to  one 
side  of  a  small  area  from  which  they  had  fallen  out,  admitting 
microorganisms  to  the  dentin.  The  same  spreading  along  the 
dento-enamel  junction  is  present,  though  in  less  degree  than  the 
average  of  cases.  An  examination  of  this  case  will  show  the 
liability  of  extension  along  the  dento-enamel  junction  under- 
mining the  incisal  angle  before  an  exposure  of  the  pulp  would 
occur,  a  thing  that  frequently  happens  to  the  incisors  when 
there  is  a  lack  of  watchfulness  of  the  progress  of  decay.  This 
was  not  a  young  tooth,  as  shown  by  the  wear  of  the  cusp,  which 
has  exposed  an  area  of  dentin.    A  trace  of  a  hyaline  zone  is 


Fio.   131. 


Fig.  132. 


Fig.  131.  A  beginmng  decay  in  the  distal  surface  of  a  lateral  incisor  from  which  the  enamel 
rods  are  falling  away  and  progress  of  decay  has  begun  in  the  dentin.  A  delicate  hyaline  area  stretches 
away  toward  the  pulp  chamber. 

Fig.  132.  A  decay  in  a  worn  cuspid  that  has  made  greater  progress.  This  picture  is  liable  to 
^ve  a  false  impression  for  the  reason  that  the  cut  is  a  little  to  the  side  of  the  central  area  and  shows 
the  enamel  penetrated  with  the  enamel  rods  still  in  position,  when,  in  fact,  the  cavity  was  open 
through   the  enamel. 

15b 


Fia.  133. 


Fig.  133.  A  more  considerable  decay  in  the  distal  surface  of  a  central  incisor  in  which  the 
undermining  of  the  enamel  is  less  than  usual.  In  such  a  case  the  labial  or  lingual  plate  of  the  enamel 
may  be  found  undermined. 


CAKIES    AS    A    WHOLE.       ITS    CLINICAL   FEATURES.  109 

seen  streaking  away  to  the  pulp  chamber  from  that  as  well. 
These  shadows  occur  in  abrasions  the  same  as  in  caries,  but 
usually  are  not  so  prominent.  Whatever  else  these  zones  of 
shadow  may  be,  they  express  a  decisive  injury  to  the  dentinal 
fibrils.  A  still  more  extended  invasion  of  dentin  is  photo- 
graphed in  Figure  133.  This  is  not  an  inordinately  large  cavity, 
but  one  that  is  easily  managed  in  filling  operations.  However, 
even  in  this,  one  is  liable  to  find  the  labial  or  lingual  enamel 
plates  considerably  undermined  by  extensions  of  decay  along  the 
dento-enamel  junction.  It  should  be  noted  particularly  that 
many  of  the  incisors  are  thin  labio-lingually  at  the  point  first 
invaded  by  decay,  and  a  comparatively  moderate  extension  along 
the  dento-enamel  junction  may  cause  such  injury  to  the  labial 
enamel  plate  as  to  make  a  decisive  esthetic  blemish.  This  can  be 
avoided  only  by  careful  watchfulness  over  these  teeth  to  see 
that  caries  in  them  receives  early  attention. 

Material  for  the  illustration  of  this  class  of  decays  is  exceed- 
ingly difficult  to  obtain  and  much  dependent  upon  accident.  This 
is  exhibited  in  Figure  79.  In  this,  decay  had  practically  de- 
stroyed the  central  incisor  by  exposure  of  the  pulp  before  the 
apex  of  the  root  had  closed  sufficiently  to  permit  of  a  root  filling. 
The  case  exhibits  in  a  striking  manner  the  breadth  mesio-distally 
of  the  pulp  chamber  at  this  tender  age  of  the  child,  the  proximity 
to  the  pulp  of  the  usual  points  of  the  beginning  of  caries,  the 
small  amount  of  dentin  through  which  decay  must  penetrate  to 
expose  the  pulp,  and  strongly  suggests  the  watchfulness  that 
should  be  had  over  such  teeth  in  families  highly  susceptible  to 
caries.  This  is  an  ugly  thing  to  happen,  but  it  gave  an  excellent 
picture  of  beginning  caries  and  the  form  of  the  penetration  of 
enamel  in  the  distal  surface  of  the  tooth. 

Gingival,  Third  Decays  in  Labial  and  Buccal  Surfaces. 

ILLUSTRATIONS:    FIGURES  134-141. 

Principal  clinical  features:  (1.)  The  earliest  beginning 
of  decay  is  a  line  of  whitening  of  the  enamel  running  mesio- 
distally  near  the  free  margin  of  the  gum  in  the  middle  third  of 
the  surface  mesio-distally.  (2.)  The  spreading  of  the  decay  on 
the  surface  of  the  enamel  is  usually  confined  closely  to  exten- 
sions mesially  and  distally  toward  the  angles  of  the  tooth, 
following  the  curve  of  the  free  border  of  the  gum.  (3.)  In  cases 
of  neglect  of  cleanliness,  and  especially  in  neglect  of  the  use  of 
the  teeth  in  chewing  food,  there  may  be  extensions  occlusally 
and  also  across  the  angles  of  the  teeth  to  connect  with  proximal 


110  PATHOLOGY   OF    THE    HAED    TISSUES    OF    THE    TEETH. 

decays  on  the  mesial  and  distal  surfaces.  (4.)  In  many  cases  of 
this  class  of  caries  the  disposition  is  seen  to  spread  quickly  from 
tooth  to  tooth,  or  to  attack  a  number  of  teeth  at  the  same  time. 
(5.)  Yields  to  prophylactic  treatment  by  the  patient,  when  prop- 
erly instructed,  more  readily  than  any  other  class  of  decay. 
(6.)  Protection  from  recurrence  of  decay  after  making  fillings 
is  had  only  by  extension  of  cavities  nearly  to  the  angles  of  the 
teeth  in  the  ordinary  cases.  (7.)  Attacks  fewer  persons  than 
other  classes  of  caries,  but  is  often  very  destructive  when  a 
beginning  is  once  made.  (8.)  The  most  general  rule  is  that  gingi- 
val third  decays  occur  later  in  the  life  of  the  person  than  the 
other  classes,  but  attacks  in  early  youth  are  not  very  infrequent. 

Gingival  third  decays  in  the  labial  or  buccal  surfaces,  or  in 
both  together,  have  been  much  dreaded  by  dentists  because  of 
persistent  recurrence  to  the  mesial  and  the  distal  of  the  margins 
of  fillings,  or  to  the  gingival  when  these  have  been  made  for 
young  people.  This  difficulty  has  arisen  from  a  failure  to  study 
the  clinical  characters  and  conditions  of  occurrence  closely 
enough  to  properly  direct  the  treatment  for  its  eradication  and 
cure.  If  the  conditions  which  have  given  rise  to  the  beginning 
of  the  decay  are  not  materially  modified  by  projDhylactic  meas- 
ures, or  spontaneous  cessation,  the  disposition  to  spread  mesially 
and  distally  is  one  of  its  most  persistent  characters.  Nothing 
less  than  the  extension  of  cavities  very  nearly  to  the  angles  of 
the  teeth  attacked,  will  be  effective. 

Figure  134  is  a  photograph  of  a  cuspid  with  a  gingival  third 
decay  which  began  before  the  tooth  fully  reached  its  loosition 
in  the  arch,  or  when  the  crown  had  yet  more  than  one  third  of 
its  length  covered  by  the  free  margin  of  the  gum.  Decay  spread 
rapidly  across  the  surface  mesially  and  distally  from  the  begin- 
ning point  and  became  established  in  the  dentin.  In  the  process 
of  growth,  more  of  the  crown  of  the  tooth  was  uncovered  to  the 
gingival  of  this  decay,  the  conditions  which  caused  the  first 
beginning  remaining  or  recurring.  The  result  is  another  whit- 
ened band  of  enamel,  a  new  beginning  of  decay,  to  the  gingival 
of  the  first.  This  is  what  may  be  expected  to  occur  when  such 
decays  are  treated  by  filling,  when  they  occur  in  young  persons, 
unless  the  free  margin  of  the  gum  is  pushed  well  away  and  the 
cavity  margin  extended  so  far  to  the  gingival  as  to  include  the 
new  area  of  liability  that  must  become  exposed.  In  early  youth 
the  sufficient  persistence  of  attention  to  prophylactic  measures 
for  the  prevention  of  such  extensions  is  not  likely  to  be  so  well 
kept  up  as  to  be  a  very  safe  protection. 


Fig.  135. 


Fig.  134.  A  photograph  of  a  cuspid  with  a  decay  across  its  labial  surface.  There  is  a  decayed 
area  nmuins  across  the  surface  mcsio-distally  that  has  penetrated  the  enaiuel  and  is  making  progress 
in  the  dentin.  Undermined  enamel  has  been  breaking  away,  leaving  more  or  less  jagged  margins. 
The  beginning  of  this  decay  occurred  when  the  free  margin  of  the  gum  was  about  at  the  gingival 
margin  of  this  carious  area,  and  covered  the  portion  of  the  tooth  to  the  gingival  of  it.  As  the  tooth 
protruded  farther  through  the  gums,  more  of  the  enamel  became  exposed  and  the  conditions  producing 
decay  continuing,  or  recurring,  another  hand  of  whitened  enamel  —  beginning  decay  —  has  occurred  to 
the  gingival  of  the  first. 

Fig.  135.  Another  cuspid,  similar  to  that  in  Figure  134.  in  which  a  decay,  beginning  in  the 
enamel  when  the  tooth  was  still  half  covered  with  gum  tissue,  has  become  fLxed  in  the  dentin  and 
later  produced  a  round  opening  by  the  breaking  away  of  undermined  enamel.  "When  the  tooth  had 
protruded  farther  through  the  gum  and  the  conditions  cavising  the  beginning  of  decay  in  the  enamel 
having  passed  away,   this  appeared  much  removed  from  the  free  border  of  the  gum. 


CARIES   AS   A   WHOLE.      ITS   CLINICAL   FEATURES.  HI 

The  most  essential  condition  for  the  occurrence  of  decay  of 
this  class  is  a  saliva  favoring  certain  kinds  of  deposits  upon  the 
teeth  which  will  cover  in  attached  colonies  of  microorganisms 
in  such  a  way  as  to  protect  the  acids  formed  from  free  dissipa- 
tion in  the  general  oral  secretions.  This  may  be  such  a  condition 
as  will  enable  microorganisms  to  protect  themselves  by  the  for- 
mation of  gelatinous  plaques  (zooglea  aggregations),  or  possi- 
bly by  other  kinds  of  deposits  from  the  saliva  that  will  form  a 
membrane-like  covering  that  will  afford  a  sufficient  protection. 
It  is  a  notable  fact  that  where  any  kind  of  deposits  are  found 
upon  the  teeth,  they  are  first  to  be  seen  on  the  buccal  surfaces  at 
the  points  where  gingival  third  decays  begin.  It  is  not  any 
and  every  kind  of  aggregation  of  filth  on  the  surfaces  of  the  teeth 
that  gives  rise  to  decay.  Indeed,  some  forms  of  filth  seem  to 
prohibit  decay  instead  of  causing  it.  Some  of  the  filthiest  of 
mouths  have  no  caries,  and  in  some  cases  where  caries  has  been 
in  progress  it  seems  to  have  been  actually  stopped  by  extreme 
filthiness  in  the  same  way  as  decay  not  very  infrequently  is 
stopped  in  certain  cavities  by  the  establishment  of  putrefactive 
decomposition  in  their  interior,  as  has  been  mentioned.  Neither 
will  loose  aggregations  of  saprophytic  microorganisms,  or  of 
leptothrix  buccalis,  or  the  leptothrix  of  Vignon,  or  other  harm- 
less varieties  which  may  form  thick  masses  over  the  teeth, 
through  which  water  will  run  as  freely  as  through  a  sieve,  have 
any  influence  favoring  the  production  of  caries.  The  covering 
must  be  of  a  kind  that  will  protect  from  free  washings  by  the 
fluids  of  the  mouth,  and  in  and  under  which  the  caries  fungi 
will  grow  and  produce  acid  fermentation.  This  may  be  so  thin 
and  so  transparent  that  the  teeth  may  appear  clean  and  yet 
afford  an  effective  protection  against  the  too  free  dissipation 
of  the  acid  products  of  fermentation.  It  has  become  evident 
enough  from  clinical  observation  that  the  conditions  which  favor 
the  formation  of  these  plaques  is  one  that  is  liable  to  be  inter- 
mittent. It  comes  and  goes.  Decays  of  the  gingival  third  of 
buccal  and  labial  surfaces  are  especially  liable  to  start,  to  stop, 
and  to  start  again.  Their  exposed  situation  renders  them  more 
sensitive  to  fluctuations  of  conditions  than  decays  situated  in 
protected  localities.  This  is  said  of  decays  of  the  enamel  in 
which  enamel  rods  have  not  fallen  away  exposing  the  dentin  to 
invasion  by  microorganisms.  Once  caries  is  implanted  within 
the  dentin,  it  will  most  generally  persist,  even  when  there  is 
complete  immunity  to  the  beginnings  of  caries  on  the  enamel. 

Figure  135  shows  a  decay,  situated  centrally  in  the  labial 


112  PATHOLOGY   OF   THE   HAED   TISSUES   OF   THE   TEETH. 

surface  of  a  cuspid,  which  has  progressed  in  the  dentin,  under- 
mining the  enamel,  which,  by  breakage,  has  now  formed  a  round 
opening.  At  a  time  when  this  tooth  was  taking  its  place  in  the 
arch  and  was  uncovered  by  the  gum  tissue,  only  to  about  that 
point,  a  decay  penetrated  the  enamel  and  became  seated  in  the 
dentin.  The  particular  form  of  the  beginning  in  the  enamel 
is  now  lost  by  breakage  from  backward  decay,  but  we  know  from 
many  observations  of  such  cases  that  it  was  in  a  line  across  the 
central  portion  of  the  present  dark  area.  As  the  tooth  pro- 
truded farther  through  the  gum,  the  conditions  causing  the 
beginning  of  decay  in  the  enamel  passed  away  and  did  not  retui'n, 
but  the  decay  established  in  the  dentin  continued.  Had  the  orig- 
inal beginning  failed,  ever  so  little,  to  penetrate  the  enamel  and 
admit  microorganisms  to  the  dentin,  the  progress  would  have 
ceased  entirely.  Later,  a  blackened  blemish  of  the  enamel  would 
have  remained  to  show  where  decay  had  begun.  Many  of  these 
may  be  found  in  any  box  of  extracted  teeth. 

A  rare  position  of  decay  on  the  lingual  surface  of  a  cuspid 
is  shown  in  Figure  136,  which,  from  what  is  left  of  the  lingual 
surface,  seems  to  have  begun  as  a  pit  decay,  beginning,  probably, 
in  pits  at  the  junction  of  the  lingual  developmental  grooves  with 
the  linguo-gingival  groove  or  pits  along  the  lines  of  these.  (See 
"Descriptive  Anatomy  of  the  Human  Teeth" — Black,  Figures 
5  and  20.)  These  grooves  are  unusually  prominent,  and  one 
undecayed  pit  remains  in  view.  The  case  shows  how  decays  may 
sometimes  begin  in  the  most  unusual  positions  and  how  difScult 
it  may  become  to  define  the  local  conditions  causing  them  after 
the  immediate  surroundings  have  been  destroyed. 

The  gingival  third  decays  in  the  buccal  surfaces  of  the 
bicuspids  and  molars  are  not  materially  different  from  labial 
surface  decays.  They  exhibit  similar  characters  in  both  their 
beginning  and  in  their  disposition  to  spread  along  the  gum 
margin  mesially  and  distally.  In  the  photograph  of  the  upper 
molar.  Figure  137,  two  considerable  areas  of  loss  of  enamel  rods 
appear  in  an  area  of  rather  faint  whitening  stretching  across 
the  buccal  surface.  Figures  138,  139,  photographs  of  a  third 
molar,  show  the  wild  race  of  destruction  that  sometimes  befalls 
these  teeth  when  caries  is  allowed  to  go  on  unchecked  by  any 
sort  of  cleaning.  For  these  illustrations,  the  cementum  has 
been  tinged  with  a  selective  anilin  stain  to  show  the  gingival 
line  distinctly  in  order  to  bring  prominently  into  view  that  por- 
tion of  the  enamel  covered  by  the  free  border  of  the  gum,  illus- 
trating its  protection  from  the  beginnings   of  caries.     This 


FiQ.  136.  A  photograph  of  the  lin^ial  svirfaco  of  a  cuspid  with  a  broad  open  cavity.  From 
what  remains  of  the  surface  of  the  tooth,  it  is  seen  that  there  is  an  unusually  prominent  lingual 
groove  on  the  left  side  of  the  picture,  in  the  line  of  which  a  small  dark  pit  appears.  This  indicates 
that  there  were  other  and  deeper  pits  in  this  surface  in  which  decay  in  this  unusual  position  started. 
The  case  illustrates  the  fact  that  often  decays  in  unusual  pwsitions  have  occurred  because  of  some 
imperfection  which  has  furnished  a  place  of  lodgment,  and  the  imperfection  has  been  wholly  destroyed 
by  the  decay,  leaving  no  sign  explaining  the  cause. 

16 


Fig.  137.     A  molar  sliowing  two  beginning  points  of  decay  on  the  buccal   surface.     A   whitened 
line  running  meeio- distal ly  was  apparent  on  this  tooth,  but  the  engraver  failed  to  show  it. 

16a 


Flu.   138. 


Figs.  138,  139.  Two  photographs  of  a  lower  molar  tooth,  in  which  caries  proceeding  from  a 
buccal  surface  decay  and  a  mesial  surface  decay  have  met  across  the  angle.  Figure  138  shows  the 
wide  range  of  the  decay  of  the  buccal  surface.  Figvire  139  shows  the  mesial  surface  decay  as  a  broad, 
whitened  area,  from  which  no  enamel  rods  have  fallen  away.  This  meets  the  buccal  surface  decay 
across  the  angle  of  the  tooth.  This  picture  also  shows  the  breaking  away  of  the  undermined  enamel 
of  the  buccal  surface  to  advantage.  The  cemcntum  of  this  tooth  was  stained  selectively  with  an  anilin 
dye  to  bring  the  gingival  line  into  prominence,  showing  the  influence  of  the  free  border  of  the  gum  in 
protecting  the  enamel  from  beginnings  of  caries. 


Fig.  140. 


Fid.   140.     A  negk'ctcd  decay  of  the  buccal  surface  of  a  lower  luobr,  sliowiug  the  tiiore  conunon 
form  those  decays  assume. 


FiQ.   141.     A  photograph  of  an  upper  first  molar  that  was  misplaced   toward   the  cheek  and   but 
partially  erupted.     When  removed,  decay  of  the  enamel  had  begim  over  all  of  the  exposed  surface. 


FlQ.   142. 


FlQ.   143. 


Fig.   144. 


Fio.  145. 


.  ^V."^-    1^2145    inclusive.      Photographs  of   a   lower   first   molar   with   beginning  decay   completely 

encircling  the  crown,    following  closely  the  free  margin  of  the  gum   in  every  part.  Figure   142    the 

mesial  surface;     Figure    113,   the  buccal   surface;     Figure   144,    the   distal   surface;  Figure   145.   the 
lingual  surface. 


CABIES   AS   A    WHOLE.      ITS   CLINICAL   FEATURES.  113 

appears  to  oest  advantage  in  Figure  138.  In  Figure  139  it  is 
seen  that  the  decays  beginning  in  the  mesial  and  the  buccal  sur- 
faces have  become  connected  across  the  mesio-buccal  angle  of 
the  tooth  by  a  comparatively  narrow  neck.  The  pictures  illus- 
trate the  riotous  progress  sometimes  seen  in  buccal  decays 
under  exceptionally  unfavorable  conditions.  Figure  140  exhibits 
another  neglected  buccal  decay,  which  is  a  more  ordinary  exam- 
ple of  the  form  and  extent  of  these  when  they  are  left  to  take 
their  own  course.  It  will  be  noticed  that  this  has  not  passed  the 
angles  of  the  tooth.  These  decays  will,  of  course,  burrow  along 
the  dento-enamel  junction,  the  same  as  others,  and  in  that  way 
destroy  the  enamel  by  backward  decay  to  the  gingival  line,  allow- 
ing the  free  margin  of  the  gum  to  fall  into  the  cavity. 

Figure  141,  a  photograph  of  an  upper  third  molar,  presents 
an  anomalous  condition.  In  coming  into  position  it  deviated 
backward  and  to  the  buccal  from  the  normal,  and  seemed  to 
have  stood  for  some  time  with  but  a  part  of  its  crown  through 
the  gum.  When  removed,  the  whole  of  its  exposed  surface  was 
whitened  by  beginning  decay. 

Spbeading  of  Decay  Abound  the  Teeth. 

ILLUSTRATIONS:    FIGURES  142-145. 

In  what  has  been  written  thus  far  of  dental  caries,  the  idea 
has  been  developed  that,  when  decay  occurs  on  proximal  sur- 
faces, the  tendency  to  superficial  spreading  is  from  the  starting 
point  both  buccally  and  lingually  toward  the  angles  of  the  teeth. 
Also,  that,  when  caries  begins  on  the  buccal  surfaces,  the  ten- 
dency is  to  spread  mesially  and  distally  from  the  place  of  begin- 
ning toward  the  angles  of  the  teeth.  This  is  true  of  caries  in 
these  positions  in  all  of  the  teeth,  but  more  especially  of  the 
bicuspids  and  molars.  A  fewer  number  occur  in  the  front  teeth 
as  well.  It  has  also  been  stated  that  in  a  few  instances  under 
specially  unfavorable  conditions  this  decay  crosses  the  angles 
of  the  teeth  and  the  proximal  and  buccal  decays  join  each  other. 
This  crossing  of  the  angles  of  the  teeth  is  the  rarest  of  all  of  the 
spreading.  It  then  requires  only  that  decay  shall  also  occur 
similarly  on  the  lingual  surfaces  in  order  to  complete  the  circle 
of  the  tooth.  This,  though  much  more  rare,  occurs  also.  This 
appears  in  the  case  of  the  lower  second  molar  tooth,  four  photo- 
graphs of  which  are  shown  in  Figures  142-145,  inclusive.  Fig- 
ure 142  shows  the  mesial  surface  with  a  broad,  whitened  area 
of  carious  enamel  stretching  from  angle  to  angle,  in  which  the 

17 


114  PATHOLOGY   OF   THE   HAKD   TISSUES   OF   THE   TEETH. 

enamel  rods  have  begun  to  fall  away  at  one  point  only.  Figure 
143  is  a  photograph  of  the  buccal  surface  with  the  whitened 
area  also  stretching  from  angle  to  angle,  the  shadow  obscuring 
a  small  part  at  the  mesial  angle.  The  distal  surface,  Figure 
144,  shows  dark,  but  the  decay  is  apparent,  and  on  the  buccal 
surface,  as  seen  in  this  photograph,  the  whitened  line  of  carious 
enamel  is  seen  to  advantage  as  it  rounds  to  the  occlusal  follow- 
ing the  free  margin  of  the  gum  to  join  the  distal  surface  decay. 
Finally,  the  whitened  decay  on  the  lingual  surface.  Figure  145, 
is  seen  streaking  away  from  the  decay  in  the  mesial  surface 
in  a  curved  line,  which  is  lost  in  shadow  as  it  approaches  the 
distal  angle,  completing  the  circle  of  the  tooth. 

The  pictures  of  this  series  are  the  final  illustrations  for  the 
explanation  of  the  tendencies  to  spreading  superficially  on  the 
surface  of  the  enamel  and  the  direction  of  that  spreading  as  one 
of  the  principal  clinical  features  of  caries  of  the  teeth,  which 
every  dentist  should  fully  understand  and  appreciate  as  his 
guide  in  the  preparation  of  cavities  for  the  prevention  of  recur- 
rence of  decay  about  the  margins  of  fillings.  Every  one  should 
understand  distinctly  that  the  spreading  on  the  surface  of  the 
enamel  is  a  thing  entirely  different  and  apart  from  spreading 
along  the  dento-enamel  junction  and  destruction  of  the  enamel 
by  backward  decay,  together  with  the  general  invasion  of  and 
destruction  of  dentin  by  caries.  This  latter  spreads  in  every 
direction  from  the  point  of  penetration  of  the  enamel,  having  no 
respect  whatever  for  any  particular  surface  or  any  of  the  angles 
of  the  teeth.  The  spreading  along  the  dento-enamel  junction 
this  way  or  that  has  no  clinical  significance  in  connection  with 
the  recurrence  of  caries  about  fillings.  This  invasion  may  pro- 
duce broad  cavities,  cavities  of  awkward  shapes,  may  weaken  the 
tooth  by  the  destruction  of  dentin,  and,  in  these  and  other  ways, 
has  its  special  points  of  clinical  importance.  But  this  is  all 
secondary,  occurring  only  after  the  enamel  is  broken.  The  clini- 
cal importance  of  a  full  appreciation  of  the  superficial  spreading 
of  caries  on  the  enamel  has  to  do  especially  with  the  prognosis, 
with  the  probable  future  of  every  case  individually,  and  the 
rational  management  of  the  teeth  of  each  person  under  our  care. 
On  the  details  of  this  management,  the  success  or  failure  will 
depend  more  than  all  else,  supposing  always  that  the  details 
of  manipulation,  as  this  may  be  planned,  be  skillfully  executed. 
Together  with  all  of  this,  judgment  must  be  stimulated  and 
quickened  by  a  careful  study  of  the  conditions  of  immunity  and 
susceptibility  to  dental  caries. 


STSTKMIC    CONDITIONS.  115 


SYSTEMIC  CONDITIONS. 

ILLUSTRATIONS:    FIGURES  146158. 

In  what  has  been  presented  thus  far,  the  immediate  active 
cause  of  dental  caries  only  has  been  mentioned,  namely,  the 
acid  produced  at  the  spot  by  growths  of  microorganisms.  This 
presentation  would  be  incomplete  without  the  mention  of  other 
factors.  "While  caries  of  the  teeth  is  the  most  prevalent  disease 
known  to  man,  those  in  dental  practice  who  have  not  made  a 
careful  study  of  the  teeth  of  persons  who  have  no  need  for  dental 
operations  perhaps  do  not  realize  how  many  are  immune  to 
caries  of  the  teeth.  Many  grow  up  from  childhood  and  pass  on 
to  old  age,  without  ever  having  a  carious  tooth.  These  persons 
are  aways  to  be  found,  if  we  look  for  them. 

In  the  mouths  of  these  persons  the  same  microorganisms 
are  found  growing,  and  growing  as  abundantly,  as  in  the  mouths 
of  persons  who  are  very  susceptible  to  caries.  In  an  examination 
of  the  fluids  of  the  mouth  in  these  persons,  it  is  also  found  that 
the  saliva  is  as  acid,  as  shown  by  tests  with  litmus  paper,  as 
in  persons  who  have  caries  of  the  teeth.  Cultures  of  micro- 
organisms from  those  immune  persons  have  been  made  over 
and  over  again,  and  it  has  been  found  that  these  microorganisms 
are  of  the  same  character  and  species  and  produce  the  same 
results  in  culture  media  as  do  microorganisms  taken  from  the 
mouths  of  those  who  are  very  susceptible  to  caries.  Some  of 
these  persons  have  been  followed  for  years,  occasional  examina- 
tions and  cultivations  being  made,  so  as  to  leave  no  possible 
doubt  as  to  the  general  facts.  Therefore,  there  is  something 
lying  over  beyond  the  active  growth  of  microorganisms  and  acid 
formation  by  them,  controlling  caries  of  the  teeth.  "We  have, 
therefore,  persons  who  are  predisposed  to  caries  of  the  teeth 
and  persons  who  are  immune  to  caries  of  the  teeth. 

A  predisposition  to  disease  is  generally  considered  to  be  a 
condition  of  the  body  juices  and  cells  which  renders  the  person 
liable  to  that  particular  disease.  We  do  not  always  know  in 
what  that  condition  consists,  but,  from  the  developments  thus 
far,  we  know  it  to  be  dependent  upon  some  material  form  or 
combination  of  matter.  "We  do  not  know  this  now  of  all  diseases, 
but  we  do  know  it  of  some.  Bacteriologists  and  chemists  are 
succeeding  in  demonstrating  the  material  nature  of  the  causes  of 
disease  by  finding  alexins,  antitoxins,  etc.,  and  the  conditions 
in  which  these  are  produced  and  in  which  they  are  not  produced. 


116  PATHOLOGY    OF    THE    HABD    TISSUES    OF    THE    TEETH. 

An  antitoxin  will  prevent  persons  taking  a  certain  disease. 
For  instance,  the  antitoxin  of  diphtheria,  if  properly  applied  in 
time  during  a  diphtheria  epidemic,  will  prevent  children  from 
taking  diphtheria.  It  acts  as  a  control.  Here  we  are  introducing 
into  the  blood  a  material,  or  combination  of  matter,  which  con- 
trols or  prevents  the  development  of  disease.  So  many  of  these 
have  now  been  proved  as  to  give  the  strongest  possible  evidence 
that  all  of  them  are  material.  "We  go  through  the  process  of 
vaccination  to  produce  a  material  condition  in  our  own  bodies 
that  will  prevent  us  from  taking  smallpox.  An  antitoxin  is 
produced  in  the  blood,  in  the  juices  in  the  tissues  of  our  bodies, 
which  is  antagonistic  to  the  disease  known  as  smallpox.  In 
these  ways  we  are  learning  to  control  a  number  of  the  most 
destructive  diseases. 

Disease  is  also  said  to  be  hereditary.  Tuberculosis  has  been 
reputed  to  be  intensely  hereditary.  That  condition  depends 
upon  some  material  element  in  the  body;  just  what  this  is,  we 
may  not  know  now.  A  person  is  not  born  with  tuberculosis ;  it 
is  not  transmissible  from  parent  to  child,  but  the  child  is  born 
with  a  material  constitution  of  body  which  renders  it  particu- 
larly liable  to  contract  the  disease,  but  it  will  not  have  tubercu- 
losis unless  exposed  to  the  tuberculosis  infection;  but  it 
contracts  it  more  readily  than  other  people.  There  is  that  ele- 
ment in  the  body  juices  and  tissues  which  enables  that  particular 
microorganism  to  grow  more  freely  or  produce  more  injury 
than  in  other  persons.  That  is  what  constitutes  a  hereditary 
predisposition  to  disease. 

We  find  in  certain  families  a  hereditary  predisposition  to 
caries  of  the  teeth  that  is  strongly  marked.  If  a  family  of  chil- 
dren is  presented  for  treatment  and  it  is  found  that  the  father 
or  mother,  or  both,  have  suffered  severely  in  early  youth  from 
caries  of  the  teeth,  we  may  be  reasonably  sure  that  the  children 
will  suffer  likewise.  We  find  this  almost  universally  true  of 
families.  Not  only  this,  but  we  find  in  very  many  instances 
that  the  first  beginning  and  the  order  of  progress  will  be  in 
the  same  teeth,  and  otherwise  similar  in  character  and  form.  I 
have  followed  these  peculiarities  now  through  four  generations 
of  persons,  and  find  these  particular  characteristics  to  be  heredi- 
tary. There  are  certain  conditions,  however,  that  seem  to  influ- 
ence these  hereditary  peculiarities  in  a  very  marked  degree.  It 
is  noted  perhaps  most  in  those  families  that  come  from  Europe 
and  settle  in  America.  In  these,  where  the  parents  are  immune, 
or  very  nearly  immune,  to  caries  of  the  teeth,  we  find  them  pre- 


SYSTEMIC   CONDITIONS.  117 

senting  us  with  children  who  are  very  susceptible  to  caries. 
There  seems  to  have  been  some  change  brought  about  in  the 
change  of  climate  or  conditions  under  which  they  live.  The 
reverse  of  this  has  been  noted  in  a  few  instances.  Also,  it  has 
been  noted  that  parents  who  have  come  to  the  city  from  the 
country  and  who  did  not  suffer  much  from  caries,  present  us 
children  reared  in  the  city  who  suffer  greatly  from  caries.  Here 
again  a  change  in  the  mode  of  living  seems  to  have  influenced 
the  hereditary  factor.     These  changes  are  quite  frequent. 

The  jiredisposition  to  caries  is  much  stronger  in  youth  and 
tends  to  disappear  as  persons  arrive  at  mature  age.  Indeed, 
caries  of  the  teeth  is  a  disease  of  youth  rather  than  of  adult 
age,  for  it  is  now  found,  after  much  careful  observation  on  this 
point,  that  if  caries  of  the  teeth  occurring  in  youth  is  well  and 
successfully  managed,  very  little  caries  will  occur  in  after  life 
in  the  majority  of  persons.  Cases  of  persistence,  however,  of 
the  beginnings  of  caries  at  new  points  are  sufficiently  plentiful ; 
and,  also,  cases  are  frequently  occurring  where  persons  have 
been  immune  from  caries  for  many  years,  and  suddenly  we  find 
their  teeth  decaying  very  badly,  showing  that  there  has  been 
a  marked  change  in  the  predisposition  to  this  disease. 

Again  in  pregnant  women  there  is  often  a  renewal  of  the 
conditions  giving  rise  to  caries  of  the  teeth  that  are  apt  to  con- 
tinue also  during  the  period  of  lactation.  It  has  happened  that 
girls  who  have  grown  up  under  the  best  of  care  and  arrived  at 
adult  age  with  many  fillings,  perhaps,  but  with  teeth  in  good 
condition  and  showing  unmistakable  signs  of  immunity  to  decay, 
have  married,  and,  during  their  first  pregnancy,  developed  a 
considerable  number  of  new  cavities  in  which  decay  progressed 
rapidly.  This  recurrence  of  susceptibility  is  not  at  all  uncom- 
mon, and  marks  a  change  in  bodily  conditions  with  consequent 
changes  in  the  oral  secretions,  favoring  the  development  of 
caries  of  the  teeth. 

The  fact  that  caries  of  the  teeth  is  more  prevalent  in  chil- 
dren than  in  adults,  conforms  with  what  is  known  of  many  other 
diseases.  We  have  a  whole  list  of  diseases  that  are  peculiar  to 
children,  as  measles,  chicken-pox,  diphtheria,  whooping-cough, 
scarlet  fever,  etc.  As  persons  arrive  at  adult  age,  the  predispo- 
sition to  these  diseases  passes  away,  or  immunity  comes;  and 
this  is  so  complete  that  it  is  rare  to  find  an  adult  person  suffering 
from  this  class  of  diseases.  They  are  practically  confined  to 
children. 

Generally  also  they  are  self-limiting  diseases.     This  term 


118  PATHOLOGY   OF   THE   HAKD   TISSUES   OP   THE   TEETH. 

"self -limiting"  is  applied  to  those  diseases  which  run  a  specific 
course  and,  if  the  patient  has  withstood  the  attack,  tend  to  recov- 
ery at  about  a  certain  period.  In  all  of  these,  it  is  found  that 
there  has  been  a  change  in  the  blood,  which  renders  the  person 
immune,  and  this  is  known  as  the  development  of  an  antitoxin, 
which  remains  more  or  less  permanent  in  the  blood.  In  some  of 
the  diseases  it  seems  to  become  a  permanent  fixture,  as  in  small- 
pox. In  others,  it  disappears  after  a  time  more  or  less  com- 
pletely, and  the  person  again  becomes  susceptible.  In  this  way, 
children  may  have  scarlet  fever  and  some  other  of  the  chil- 
dren's diseases  more  than  once  before  they  become  permanently 
immune.  In  other  cases,  susceptibility  to  disease  seems  to  go 
and  come.  At  one  time  a  person  exposed  to  a  contagious  disease 
apparently  under  all  conditions  that  would  favor  its  develop- 
ment, goes  free.  The  same  person  at  other  times,  with  probably 
other  conditions  of  the  body  juices  and  cells,  will  take  the  disease 
readily  under  otherwise  similar  conditions.  Most  of  the  microbic 
diseases  have  some  one  or  more  of  the  peculiarities  that  have 
been  mentioned,  but  there  are  some  that  are  not  in  any  wise  self- 
limited.  Tuberculosis  is  one  of  these.  Although  purely  a 
microbic  disease,  there  seems  to  be  no  self-limiting  effect. 

Something  similar  to  the  changes  that  happen  in  suscepti- 
bility and  immunity  to  other  diseases  must  occur  in  caries  of 
the  teeth,  for  to-day  it  is  only  upon  this  ground  that  we  can 
explain  the  conditions  of  susceptibility  and  immunity  that  are 
so  prominently  before  us.  Formerly,  the  susceptibility  or 
immunity  of  the  teeth  to  decay  was  differently  explained.  It 
was  supposed  that  hardness  or  softness  of  the  teeth,  the  amount 
of  calcium  salts  they  contained,  was  in  a  large  degree  the  con- 
trolling factor,  and  under  that  supposition,  when  the  teeth  of 
children  were  seen  to  be  decaying  badly,  the  interpretation  was 
that  the  teeth  were  soft  or  poorly  calcified.  If  the  child  grew 
up  without  decay  of  the  teeth,  the  interpretation  was  that  the 
teeth  were  hard  and  firm  and  for  that  reason  did  not  decay.  It 
was  on  this  ground  that  the  effort  was  made  to  explain  the 
variations  of  susceptibility  and  immunity  of  which  we  have 
spoken. 

Physical  Characters  of  the  Teeth. 

The  idea  that  some  teeth  are  hard  and  some  teeth  are  soft, 
grew  up  in  the  minds  of  the  dental  profession  and  of  the  laity 
many  years  ago,  and  this  was  generally  regarded  as  a  fixed  fact. 


SYSTEMIC   CONDITIONS.  119 

These  differences  were  supposed  to  be  considerable,  and  caries 
was  supposed  to  be  severe  in  teeth  that  were  very  soft. 

The  fact  is,  that  heretofore,  when  it  was  discovered  that 
the  teeth  of  an  individual  were  decaying  very  rapidly,  the  inter- 
pretation was  that  the  teeth  were  poorly  calcified  and  were  soft. 
If,  after  careful  treatment,  little  or  no  decay  occurred,  it  was 
supposed  that  the  teeth  had  become  hard  and  firm.  Again,  if 
a  person  had  arrived  at  maturity  with  little  or  no  decay  of  the 
teeth  and  later  it  was  discovered  that  the  teeth  were  decaying 
very  badly,  the  interpretation  was  that,  while  the  teeth  had  been 
very  good  in  their  structure,  something  had  happened  to  cause 
them  to  become  soft,  and  therefore  they  decayed  badly.  In  this, 
the  observation  of  clinical  facts  has  been  correctly  reported. 
Many  persons  have  grown  to  maturity  without  decay  of  the  teeth 
and  afterward  their  teeth  have  decayed  very  badly.  It  was  quite 
generally  held  that,  during  pregnancy  and  lactation,  the  teeth 
of  the  mother  were  robbed  of  calcium  salts  to  build  up  the  bones 
of  the  fetus.  This  was  because  of  the  general  observation  that 
during  such  periods  the  teeth  of  women  suffer  more  from  caries 
than  during  other  periods.  These  observations  were  shown  to 
be  correct  by  the  testimony  of  many  observers,  and  lines  of 
treatment  were  undertaken  for  the  correction  of  the  supposed 
loss  of  calcium  salts  in  the  teeth.  A  large  proportion  of  people 
who  have  decay  in  their  youth,  will,  if  that  decay  is  well  cared 
for,  cease  to  have  much  decay  later  in  life.  This  gave  rise  to 
the  general  opinion  that  the  teeth  were  inclined  to  become  hard 
with  advancing  age.  These  observations  were  carried  on  and 
discussed  more  or  less  for  years,  serving  to  fix  the  interpretation 
mentioned  in  the  minds  of  both  the  dentists  and  the  people.  In 
fact,  there  seems  to  have  been  no  question  as  to  the  correctness 
of  the  interpretation. 

In  1895  I  published  a  series  of  studies  {Dental  Cosmos,  Vol- 
ume 37,  page  353)  which  were  undertaken  to  determine  the  facts 
as  to  the  differences  in  the  physical  properties  of  the  teeth  with 
reference  to  hardness  and  softness,  as  represented  by  the  per- 
centage of  calcium  salts  in  the  dentin,  and  the  relation  this  held 
to  caries.  The  results  of  this  investigation  are  given  in  great 
detail,  but  for  our  purpose  very  little  of  it  need  be  repeated. 
The  results  surprised  myself  as  much  as  they  surprised  others, 
for  it  was  found  that  there  were  no  differences  of  consequence. 
I  give  here  a  summary  of  that  investigation,  which  will  show 
the  actual  facts  and  also  that  the  interpretation  of  soft  teeth 
and  hard  teeth,  as  that  interpretation  then  stood  in  the  minds 


120 


PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 


Genebal  Summary  of  Eesults  of  Physical  Examinations 

OF  THE  Teeth. 


Per  cent 

of 
water 

Per  cent 

Per  cent 

No.  of 

Average 

No,  of 

Specific 

of 

of 

case3. 

Age 

Teeth. 

Gravity 

calcium 
salts 

organic 
matter. 

Average  for  total  number  of 

teeth 

Ill 

32.33 

268 

2.092 

11.06 

63.54 

25.36 

The  highest  percentage 

2.133 

13.56 

65.75 

27.59 

The  lowest  percentage 

2.036 

9.32 

61.08 

23.26 

.097 

4.24 

4.67 

4.33 

Average  for  persons  under  15 

years  old  

11 

11. 

13 

2.066 

11.89 

62.26 

25.92 

Average  for  persons  15  years 

old  and  under  20 

8 

17. 

9 

2.080 

11.46 

63.18 

25.33 

Average  for  persons  20  years 

old  and  under  25 

20 

21.55 

48 

2.081 

11.47 

63.43 

25.23 

Average  for  persons  25  years 

15 

25.93 

43 

2.086 

11.27 

63.44 

25.28 

Average  for  persons  30  years 

old  and  under  40 

26 

33. 

72 

2.092 

10.84 

63.42 

25.66 

Average  for  persons  40  years 

old  and  under  50 

12 

42.66 

38 

2.094 

10.91 

63.73 

25.34 

Average  for  persons  50  years 

old  and  under  60 

10 

53. 

19 

2.105 

10.85 

63.83 

25.29 

Average  for  persons  60  years 

and  over 

10 

63.60 

27 

2.109 

10.66 

64.56 

24.81 

Average  for  males  20  years  old 

and  under  30 

12 

24 

2.082 

63.30 

Average  for  females  20  years 

old  and  under  30.     

26 

67 

2.083 

63.51 



Average  for  males  30  years  old 

and  under  40    

12 

18 

2.090 

63.35 

Average  for  females  30  years 

old  and  under  40 .... 

14 

54 

2.094 

63.48 

Average  for  males  40  years  old 

and  under  50 . 

6 

19 

2.093 

63.54 

Average  for  females  40  vears 

old  and  under  50 

6 

19 

2.094 

63.92 

Increase  due  to  age 

Decrease  due  to  age. 

.043 

2.30 

1.29 

1.12 

Average  for  persons  who  lost 

their  teeth  from  diseases  of 

the  peridental  membranes  . . 

15 

50. 

51 

2.101 

10.88 

62.90 

25.19 

Average  for  cases  in  which  the 

teeth  are  classed  as  bad.  .  . 

32 

28. 

121 

2.087 

11.25 

63.33 

25.49 

Average  for  cases  in  which  the 

teeth  are  classed  as  good. 

63 

33.53 

105 

2.090 

11.16 

63.53 

25.31 

Average  for  cases  in  which  the 

teeth  are  classed  as  fair  . 

16 

36.19 

42 

2.090 

10.95 

63 .  56 

25.48 

Average  for  perfect  teeth 

42 

36.26 

103 

2.095 

11.03 

03 .  59 

25.36 

Average  for  carious  teeth  .  . 

91 

31.5 

165 

2.091 

11.06 

62.50 

25.36 

SYSTEMIC    CONDITIONS.  121 

of  the  dental  profession  and  of  the  laity  as  well,  was  wrong. 
There  had  never  been  any  substantiation  of  that  interpretation 
by  careful  physical  examination  of  the  teeth  themselves. 

This  summary  speaks  for  itself  and  shows  that  the  greatest 
difference  in  the  calcium  salts  in  the  dentin,  including  all  exag- 
geration that  might  arise  from  errors,  was  4.35  per  cent,  and  the 
usual  range  of  difference  was  very  much  less  than  this.  The  dif- 
ferences due  to  age  are  also  given,  and  it  is  found  to  be  2.30  per 
cent.  When  we  consider  that  ivory,  or  the  tusk  of  the  elephant, 
has  20  per  cent  less  of  calcium  salts  than  the  human  teeth,  and 
we  consider  its  hardness  as  compared  with  the  human  dentin, 
we  will  see  that  these  slight  differences  in  the  amount  of  calcium 
salts  can  amount  to  nothing  whatever  as  rendering  the  teeth 
more  or  less  liable  to  dental  caries.  It  is  clearly  shown  in  the 
comparison  of  the  amount  of  calcium  salts  in  the  teeth  of  those 
whose  teeth  decayed  badly  with  the  amount  in  the  teeth  of  those 
immune  to  decay,  that  there  is  no  difference  whatever.  Teeth 
that  decay  badly  have  just  as  much  calcium  salts,  are  just  as 
heavy  and  just  as  hard,  as  teeth  of  persons  immune  to  caries. 
Therefore,  while  the  fact  in  regard  to  caries  being  severe  in 
this  person's  mouth,  while  the  teeth  of  another  person  escape 
caries  entirely,  was  a  perfectly  correct  observation,  to  attribute 
this  to  the  softness  of  the  teeth  in  the  one  and  the  hardness  of 
the  teeth  in  the  other,  was  a  wrong  interpretation;  but  this 
interpretation  has  become  so  fixed  in  the  minds  of  men  that  it  is 
very  difficult  indeed  for  many  of  the  older  men,  particularly,  to 
change  their  minds  upon  this  point.  It  is  perhaps  well  for  the 
human  family  that  opinions  so  widely  held  should  have  great 
weight  in  all  matters  pertaining  to  human  welfare.  They  should 
not  be  cast  aside  without  the  very  best  reasons  for  so  doing. 

At  the  close  of  the  paper  communicating  these  results,  the 
suggestion  was  strongly  made  that  the  causes  of  immunity  and 
susceptibility  to  dental  caries  would  necessarily  be  found  in 
conditions  of  the  general  system,  influencing  the  qualities  of  the 
mixed  fluids  of  the  mouth  by  which  the  teeth  were  surrounded. 
The  composition  of  these  fluids  influences  the  action  of  the  micro- 
organisms growing  in  them  in  such  a  way  that  caries  occurs  in 
one  person  and  not  in  another.  "While  the  elements  entering 
in  to  produce  these  differences  in  dental  caries  might  be  totally 
different  from  those  in  systemic  conditions  controlling  suscepti- 
bility or  immunity  to  other  diseases,  the  search  for  them  would 
be  conducted  on  the  same  general  principles. 

The  storm  of  disapproval  that  arose  when  these  results 

18 


122  PATHOLOGY   OF    THE    HAED    TISSUES   OF    THE   TEETH. 

were  published  was  what  might  be  expected  under  the  circum- 
stances. They  were  regarded  as  revolutionary,  and  rightly,  for 
the  results  proved  that  many  of  the  ideas  of  dental  caries  that 
had  existed  before  were  necessarily  wrong,  and  other  opinions 
must  take  the  place  of  those  which  had  been  regarded  as  correct. 
Many  arguments  were  advanced  from  time  to  time  in  the  effort 
to  sustain  the  older  view,  most  of  which  have  disappeared. 

The  haedness  and  softness  of  the  teeth  to  cutting  instru- 
ments has  troubled  a  considerable  number  of  men.  It  has  been 
difficult  for  them  to  feel  that  all  teeth  were  of  equal  hardness, 
or  nearly  so,  as  had  been  represented.  A  further  careful  study 
of  the  subject  shows  that  this  has  generally  been  due  to  differ- 
ences found  in  cutting  the  enamel  of  different  teeth,  rather  than 
in  cutting  the  dentin.  With  the  exception  of  its  tubules  running 
through  it,  the  dentin  seems  to  be  very  homogeneous  in  struc- 
ture. There  is  no  disposition  to  split  in  any  one  direction 
more  readily  than  another.  Generally  no  accretion  lines  are 
discoverable,  though  these  may  often  be  brought  in  view  by 
decalcification.  We  can  not  find  them  in  the  calcified  dentin  with 
instruments.  In  careful  experimental  work  in  cutting  dentin,  I 
have  been  unable  to  distinguish  differences  that  seem  to  be  of  con- 
sequence. In  the  crushing  strength,  quite  a  little  difference  has 
been  noted,  which  will  be  found  in  the  tables  of  the  strength  of 
dentin  accompanying  the  studies  to  which  I  have  referred. 

In  the  enamel  there  are  wider  differences  in  the  apparent 
hardness  to  cutting  instruments.  These  are  due  (1)  to  the  direc- 
tion of  approach,  (2)  and  to  differences  in  the  relation  of  the 
enamel  rods  to  each  other.  The  enamel  is  not  a  homogeneous 
structure  like  the  dentin,  but  is  composed  of  the  enamel  rods 
cemented  together  by  a  cementing  substance  which  is  less  strong 
than  the  rods  themselves  and  allows  them  to  part  on  the  line  of 
their  length  more  easily  than  in  other  directions.  When  the 
rods  lie  parallel  with  each  other,  the  enamel  splits  in  their  direc- 
tion easily  when  a  breach  has  been  made  and  a  sharp  chisel  is 
used  in  the  right  direction  on  the  margin  of  the  breach.  If  we 
undertake  to  cut  it  in  other  directions  with  steel  instruments, 
it  is  found  to  be  very  hard.  This  is  called  straight  enamel. 
Figure  146  is  a  photomicrograph  of  straight  enamel  in  which  the 
rods  lie  parallel  and  are  straight  from  the  dento-enamel  junc- 
tion to  the  surface  of  the  enamel.  This  enamel  with  straight 
parallel  rods  is  found  on  very  many  teeth;  perhaps  in  the 
majority  of  cases  we  will  find  the  enamel  rods  straight  and 
parallel,  except  over  the  cutting  edges  of  the  incisors  and  the 


xVXVv 


k^vi.,,')'  ■ 


■-^•w. 


■'■^'4 


FlQ.    146.     A    photomicrograph    of    a    section    of    enamel    having   straight    parallel    rods    running 
through  its  entire  thickness.     Such  enamel  splits  away  from  the  margins  of  a  break  very  easily. 

18a 


I'l'MV 


iiiPiiiiii 

mlimm 


.f.  •    •"; 


:l  ■'m&'mf'' 


^ 


Fig.  147.  A  ijliotuniifinyiaiih  uf  curled  enamel  in  which  Llic  inner  two-thirds  of  the  enamel  i? 
composed  of  interlaced  bundles  of  rods.  These  straijrhton  up  and  becomo  parallel  in  the  outer  one- 
third  of  the  thickness  of  the  enamel.  Such  enamel  splits  away  from  the  margin  of  a  break  with  great 
dilhcMlty  as  compared  with  enamel  having  parallel  rods. 

ISb 


Fia.   148.     A  photomiciograph  of  curled  enamel. 


Fig.  149. 


Fig.  349.  A  photomicrograph  of  the  gingival  portion  of  the  enamel  on  the  proximal  surface  of 
uii  incisor  having  curled  enamel,  showing  the  direction  of  the  enamel  rotis  in  tlie  extreme  gingival  por- 
tion.    The  cracks  in  the  specimen  indicate  the  direction  of  cleavage. 


OS'S 


6s  w  t;  c 

S      3  s 

S.g  is 


3    - 

o       ^ 


»  a.  o' 


o 

3 

S3     ■ 

U 

3-    ^ 

ri 

o"  t,-. 

H 

_j 

P 

(S 

3 

■«1 

3 

1^ 

'^ 

a* 

p 

P 

c 

-^ 

3 

e 

^ 

1 

s. 

= 

>■ 

3 

3* 

WJ 

« 

31 

•"■ 

M. 

Q 

_._  3 


"3? 

P  - 

Etc 


SYSTEMIC    CONDITIONS.  123 

cusps  of  the  molars  and  bicuspids.  We  will  find  only  a  variation 
from  the  straight  line  in  these  positions  on  many  teeth  without 
intertwining  of  bundles  of  rods.  Enamel  with  straight,  or  paral- 
lel, rods  may,  when  undermined,  be  split  off  about  the  margins 
of  a  breach  that  has  been  made  in  it  almost  as  easily  as  straight 
grain  pine,  if  it  is  touched  just  right  with  a  sharp  instrument. 
If  not  approached  in  the  right  direction,  it  is  very  hard  to  cut. 
On  the  other  hand,  many  teeth  have  enamel  over  most  of  their 
surfaces  that  is  curled;  that  is,  the  enamel  rods,  instead  of 
pursuing  a  straight  course,  are  much  interwoven  among  each 
other,  usually  in  the  form  of  small  bundles  of  rods,  twisting  in 
among  other  bundles  of  rods.  This  gives  to  the  enamel,  when 
cut  in  sections  and  etched,  a  wavy,  twisted  appearance.  This 
is  called  curled  enamel.  See  Figures  147,  148.  This  form  of 
enamel  does  not  sjilit  nearly  so  readily  as  enamel  with  parallel 
rods.  In  fact,  it  is  much  more  difficult  to  cut  it  by  ordinary 
means.  It  should  be  noted,  however,  that  in  nearly  all  cases  of 
curled  enamel,  the  rods  straighten  up  and  become  parallel  before 
reaching  quite  to  the  outer  surface.  The  checking  of  this  straight 
portion  to  the  part  that  is  curled  in  Figure  147  is  suggestive. 
Often  the  inner  half  will  be  curled  and  the  outer  half  of  the 
thickness  straight.  There  are  all  sorts  of  differences  to  cutting 
instruments  between  the  perfectly  straight  enamel,  as  shown 
in  Figure  146,  and  the  abundant  intertwining  of  bundles  of  rods 
seen  in  Figure  147.  The  gingival  portion  of  the  enamel  from  the 
labial  surface  of  an  incisor  is  represented  by  photomicrograph 
in  Figure  149,  which  presents  much  variation  in  the  direction 
of  the  rods  in  its  different  parts.  Some  places  they  are  parallel 
but  much  bent.  Then,  for  another  short  space,  they  are  much 
interwoven.  In  this  respect  the  specimen  is  rather  remarkable. 
In  the  cross  section  of  the  tooth  at  the  point  where  the  section 
was  taken,  shown  in  the  photomicrograph,  Figure  150,  the  rods 
are  neither  quite  straight  nor  quite  parallel,  but  do  not  depart 
much  from  either.  But  it  may  be  seen  how  the  rods  are  split  up 
and  clinging  across  the  crack  near  the  letter  a,  reminding  one 
of  what  occurs  in  splitting  cross-grained  wood.  One  would, 
however,  split  off  chips  from  the  cut  surface  at  a  very  easily. 
But  to  split  off  chips  from  the  cut  surface  at  b  would  be  very 
difficult,  not  because  the  rods  are  more  interwoven,  but  because 
of  the  direction  of  rods  toward  the  cut  surface.  These  differ- 
ences seem  to  have  no  reference  to  the  calcification  of  the  enamel, 
nor  the  amount  of  calcium  salts  it  may  contain.  In  studying  the 
difference  of  structure  in  its  relation  to  caries  of  the  teeth,  no 


124  PATHOLOGY    OF    THE    HAED    TISSUES   OF    THE   TEETH. 

differences  whatever  are  found.  Caries  seems  to  pass  through 
the  one  just  as  readily  as  through  the  other.  Therefore,  from 
this  phase  of  the  question,  these  differences  are  of  no  conse- 
quence whatever. 

Faults  in  the  Structuee  of  the  Enamel. 

Faults  in  the  structure  of  the  enamel,  such  as  pits  and 
fissures,  have  already  been  spoken  of  as  of  importance  in  the 
localization  of  beginnings  of  decay.  The  importance  of  these 
has  probably  been  overrated  in  the  past.  Very  few  of  the  pits 
are  properly  termed  faults.  They  are  normal  to  the  teeth.  They 
become  faults  only  when  they  are  abnormal  in  depth.  Grooves 
along  the  lines  of  junction  of  the  lobes  of  the  teeth  are  normal. 
When  these  are  of  such  depth  as  to  merit  the  term  "fissure" 
they  are  abnormal  and  are  faults.  These,  even  when  faults, 
are  in  no  proper  sense  a  cause  of  dental  caries,  but  they  furnish 
favorable  conditions  for  the  action  of  that  cause.  They  must 
be  regarded  as  giving  opportunities  for  the  beginning  of  decay 
when  conditions  otherwise  are  favorable.  But  decay  does  not 
begin  in  the  pits  of  the  teeth  of  immune  persons,  though  these 
pits  may  be  just  as  deep  and  just  as  sharp  as  the  pits  in  other 
teeth  which  do  decay  rapidly,  and  even  among  those  who 
are  very  susceptible  to  decay,  many  pits  will  be  seen  without 
decay,  in  those  teeth  that  are  decayed  upon  their  proximal  sur- 
faces. This  is  so  frequent  that  they  are  coming  up  continually 
in  the  laboratory  study  of  caries.  In  the  illustrations  accom- 
panying this  article,  these  will  be  seen  in  Figures  107,  108,  110. 
Here  we  see  that  the  pits  have  escaped  the  beginning  of  caries 
when  the  patient  has  been  sufficiently  susceptible  for  proximal 
decays  to  start  and  run  a  rapid  course.  So  many  of  these  occur 
that  we  must  regard  the  condition  of  immunity  as  entirely  suf- 
ficient to  prevent  decays  starting  in  pits,  unless  the  conditions 
locally  are  particularly  inviting.  This  may  be  said  to  be  true 
of  all  teeth  which  would  be  regarded  as  of  normal  conformation. 
We  occasionally  find  malformed  teeth  in  which  the  pits  and 
fissures  have  failed  of  closure  and  in  which  some  area  of  dentin 
is  actually  exposed.  This,  however,  is  rare.  Ordinarily,  all  of 
the  deeper  pits  have  a  fairly  good  layer  of  enamel  covering  the 
dentin,  but  this  forms  no  considerable  barrier  to  the  beginning 
of  decay,  for,  in  susceptible  persons,  the  enamel  seems  to  decay 
readily  in  such  positions,  while  in  those  who  are  not  susceptible 
there  is  no  decay  in  pits  or  elsewhere.  I  once  obtained  fourteen 
teeth,  mostly  bicuspids  and  molars,  from  the  mouth  of  a  woman 


SYSTEMIC   CONDITIONS.  125 

over  fifty  years  old,  who  had  reared  a  family  of  children,  but 
had  never  had  a  decayed  tooth.  The  teeth  were  lost  because  of 
disease  of  the  peridental  membranes.  I  split  these  with  a  fine 
saw  and  examined  carefully  the  pits  found  in  them.  They  were 
unusually  deep  and  sharp,  forming  what  seemed  to  be  unusually 
favorable  places  for  caries  to  begin,  yet  the  enamel  was  perfect 
in  the  bottoms  of  all  of  these  pits.  Still,  from  my  experience, 
I  am  convinced  that  a  well-fitted  band  of  some  considerable 
width,  immovably  fixed,  but  with  a  buccal  surface  left  without 
cement,  would  have  produced  caries  in  that  mouth.  There  are 
certainly  differences  in  the  saliva  that  favor  microorganisms 
becoming  fixed  upon  and  clinging  to  the  teeth  of  some  persons, 
while  in  other  persons  there  is  that  which  opposes  this,  and  every 
part  is  washed  so  freely  as  to  carry  away  all  acid  formed  by  any 
growths  that  may  temporarily  lie  upon  the  enamel.  The  band 
prevents  this  dissipation. 

These  pits  occur  in  the  occlusal  surfaces  of  the  teeth  of  all 
animals  that  are  omnivorous  in  their  diet,  and  should  not  be 
regarded  as  abnormal  in  man.  The  fact,  however,  that  decay 
in  them  occurs  so  frequently,  gives  abundant  evidence  that  they 
furnisli  the  opportunity  for  its  beginning.  Therefore,  if  the 
teeth  are  really  faulty  in  their  structure  so  that  there  are  open 
fissures  as  well,  decay  is  the  more  certain  to  occur.  There  are 
some  faults  in  structure  within  the  dentin  which  give  rise  to 
unusual  forms  of  cavities.  Sometimes  the  granular  layer  of 
Tomes  is  very  much  more  considerable  under  some  parts  of  the 
enamel  than  others,  inviting  the  burrowing  of  decay  in  special 
directions,  causing  irregular  forms  of  cavities.  Often,  also,  we 
find  irregular  groups  of  interglobular  spaces  in  the  dentin  into 
which  microorganisms  grow  very  readily  and  in  that  way  pro- 
duce irregularities  in  cavity  forms.  This  occurs  when  there  is 
no  appearance  of  atrophy  upon  the  enamel.  In  cases  of  atrophy, 
particularly  where  the  occlusal  surfaces  of  the  first  molars  have 
been  wrecked,  caries  is  very  likely  to  run  through  the  sheet  of 
interglobular  spaces  in  the  dentin,  usually  only  a  little  below  the 
dento-enamel  junction.  This  often  forms  a  broad,  open  cavity 
with  the  decay  still  following  this  sheet  of  interglobular  spaces 
until  finally  the  whole  occlusal  surface  is  cut  away,  the  decay 
having  extended  but  little  in  depth.  The  result  is  that  the  whole 
occlusal  surface  of  the  tooth  has  decayed,  leaving  a  blackened 
stump,  which  may  come  to  occlude  with  its  fellow  of  the  opposite 
jaw  and  do  excellent  service  in  mastication.  It  too  often  hap- 
pens, however,  that  decay  persists  in  those  portions  of  the  sheet 


126  PATHOLOGY    OF    THE    HAED   TISSUES   OP    THE   TEETH. 

of  interglobular  spaces  that  dip  down  on  the  axial  surfaces  and 
finally  reaches  the  pulp  of  the  tooth.  As  the  atrophy  occurs 
in  all  four  of  the  first  molars,  it  is  rather  rare  that  some  one 
or  more  of  them  is  not  destroyed.  These  are  the  principal  faults 
in  the  structure  of  the  teeth  that  seem  to  influence  caries.  It 
will  be  noted  that  all  of  these  faults  are  such  as  are  discoverable 
by  macroscopic  or  microscopic  examination.  No  faults  in  the 
chemical  structure  of  the  teeth  have  been  found  which  seem  to 
influence  caries  in  any  marked  degree.  Even  some  of  those 
rare  cases  in  which  the  cementing  substance  between  the  enamel 
rods  has  failed,  leaving  the  enamel  rough  and  chalky,  have  been 
found  almost  immune  to  dental  caries.  It  would  seem  that  such 
teeth  would  be  especially  liable  to  decay  early  and  quickly,  and 
they  certainly  would  do  so  if  they  were  in  the  mouths  of  suscepti- 
ble persons. 

Physiological  and  Pathological  Differences  Between  Bone 

AND  Dentin. 

ILLUSTRATIONS:    FIGURES  151155. 

Some  persons  have  seemed  to  suppose  that  the  teeth  and  the 
bones,  being  calcified  tissues,  should  have  similar  physiological 
processes  of  nutritional  change  and  of  repair,  and  that  similar 
changes  might  be  expected  as  results  of  pathological  conditions. 
It  is  well  known  that,  in  certain  diseases,  as  in  rickets,  the  bones 
become  soft  and  may  become  hard  again;  and  that  nutritional 
changes  are  going  on  continually  in  the  bones  up  to  an  advanced 
age,  if  not  during  the  whole  life,  and  that  the  bones  are  very  apt 
to  become  hard  and  brittle  as  persons  grow  older. 

In  the  study  of  the  bones,  we  find  that,  continuously,  or  at 
least  frequently,  portions  of  the  bone  are  being  removed  by 
absorption  and  replaced  by  Haversian  systems,  so  that  the  shaft 
of  a  bone  that  has  been  formed  largely  as  subperiosteal  bono,  is 
finally  converted  almost  or  quite  into  bone  composed  of  Haver- 
sian systems.  This  is  shown  in  Figure  151,  which  is  a  photo- 
micrograph from  a  cross  section  from  the  femur  of  a  young  per- 
son. In  this  figure  the  line  drawn  from  the  letter  a  passes  over 
lamina;  of  subperiosteal  bone,  which  have  not  yet  been  cut  away. 
The  lines  drawn  from  b  point  to  Haversian  systems,  where  the 
subperiosteal  bone  has  been  cut  away  and  new  bone  supplied 
in  the  form  of  circular  whorls,  with  a  canal  in  the  center  of  each, 
which  is  called  a  Haversian  system.  In  Figure  152,  a  photo- 
micrograph from  a  section  cut  lengthwise  of  the  same  bone. 


Fig.   151. 


I'lCt.  151.     A  iiluitomicrngraiih  fiom  a  cross  section  of  Iionc  from  the  hnmiui  femur  from  a  ycMitiif 
person.         a.   This  line  crosses  laminre  of  snbperiosieal   bone.  B.   These  lines  point  out   Haversian 

system  bone.    These  Haversian  systems  that  are  seen  to  form  the  bulk  of  tissue  are  formed  by  tlie  absorp- 
tion of  the  original  subperiosteal  bone  and  building  in  the  Haversian  system  bone. 


FjG.    152.     Lengthwise   section    from   the   same   bone,    as   illustrated    in   Fi^ire   151,    showing  the 
Haversian  systems  and  their  canals  cut  lengthwise.         a.  Subperiosteal  bone.  b.  A  Haversian  canal. 


fb  u  ^ 
3D? 


g  3. 
S  2 
Sa  3 


§^3 

o      o 

=  £■? 

S   "    o 


it  K2 
?5  o 


"  3  _ 


Oo 


SiS 


5-g 


j;..-.  .,-;.a..-.Ji 


Fig.  154. 


Fig.  is*.     A  photomicrograph  of  bone  in  process  of  absorption.  i.  Line  of  absorption  sliowing 

the  lacuna)  of  Ilowship. 


Fia.   155.     A   photomicrograph  of  a  portion  of  the  root  and   peridental  membrane  of  a  tooth   in 
which  an  absorption  has  been  repaired  by  a  new  growth  of  cementum.  d.  Dentin.  c.  Cementum. 

p.  Peridental  membrane.         R.  New  cementum  built  in,  in  repair  of  an  injury  by  absorption. 


SYSTEMIC    CONDITIONS.  127 

shows  the  Haversian  canals  cut  lengthwise  for  the  most  part.  In 
studying  these,  it  will  be  seen  that  nearly  the  entire  substance 
of  the  bone  as  first  formed  has  been  cut  away  and  is  replaced  in 
the  form  of  Haversian  systems,  and  in  many  of  the  bones  we  find 
no  traces  of  subperiosteal  bone  left,  except,  possibly,  on  the 
outer  surface.  In  this  cross  section,  however,  we  find  many 
patches  of  subperiosteal  bone  scattered  through  it,  though  most 
of  it  is  occupied  by  the  Haversian  system  bone.  Each  Haversian 
canal  has  its  blood  vessels.  In  many  bones  we  find  the  Haversian 
systems  have  been  cut  out  again  and  again  and  new  Haversian 
systems  built  in  their  places.  This  is  not  done  by  removing  the 
old  Haversian  systems  individually,  but  by  absorptions  that 
seem  to  run  through  the  bone  at  random,  often  cutting  out  parts 
of  these  systems  and  leaving  parts  by  which  such  additional 
cutting  and  rebuilding  is  readily  recognized. 

This  is  nature 's  manner,  or  the  physiological  plan  of  making 
nutritional  changes  in  the  bones ;  a  plan  perfectly  well  known 
to  histologists  and  physiologists.  There  is  no  such  plan  for 
nutritional  changes  in  the  human  teeth.  Normally,  there  is  no 
absorption  of  the  roots  of  the  permanent  teeth,  nor  any  absorp- 
tional  changes  going  on.  Normally,  as  a  physiological  process, 
however,  the  roots  of  the  deciduous  teeth  are  removed  by  absorp- 
tion in  the  shedding  process.  Figure  153  is  a  photomicrograph 
from  a  line  of  absorption  at  a  in  a  cross  section  of  a  deciduous 
tooth,  showing  the  peculiar  notching  known  as  the  lacunae  of 
Howship,  where  the  dentin  and  cementum  were  being  removed 
by  the  process  of  absorption.  In  the  bones  the  process  of  absorp- 
tion is  practically  the  same  in  kind  and  quality,  and  though  we 
name  the  cells  which  absorb  bone,  osteoclasts,  and  those  which 
absorb  the  roots  of  teeth,  odontoclasts,  there  is  really  no  differ- 
ence in  the  two  processes  physically  or  physiologically.  Figure 
154  is  a  photomicrograph  from  an  example  of  this  in  bone,  which 
may  be  compared  with  that  in  dentin  and  in  cementum.  An 
absorption  of  bone  is  always  repaired  with  bone.  It  may,  if  it 
is  on  the  surface,  be  repaired  by  subperiosteal  bone.  If  within 
the  bone,  it  is  repaired  by  Haversian  system  bone.  An  absorp- 
tion of  any  portion  of  a  tooth,  dentin  or  cementum,  if  repaired 
at  all,  is  repaired  with  cementum ;  no  matter  how  deeply  it  may 
have  cut  into  the  dentin,  it  is  never  repaired  by  dentin.  Many 
of  these  repairs  are  found  in  the  study  of  the  histology  of  the 
teeth,  where,  for  some  cause,  an  absorption  has  occurred,  cutting 
deeply  perhaps  into  the  root  of  the  tooth.  Several  pictures  show- 
ing this  are  published  in  my  book  on  "Periosteum  and  Peri- 


128  PATHOLOGY    OF    THE    HABD    TISSUES    OP    THE    TEETH. 

dental  Membrane."  The  photomicrograph,  Figure  155,  shows 
the  repair  of  an  absorption  which  had  occurred  in  the  root  of  a 
tooth  in  which  the  full  contour  is  rebuilt  with  cementum. 

These  illustrations  are  brought  prominently  forward  in  this 
place  as  the  histo-iDhysiological  expression  of  the  fact  that  den- 
tin possesses  no  means  of  physiological  repair.  Additions  may 
be  made  to  it  by  the  action  of  other  tissues,  but  dentin  never 
repairs  itself.  It  is  never  repaired  by  dentin  under  any  circum- 
stances, excepting  such  as  may  be  done  by  calcifications  occur- 
ring in  the  pulp  chamber.  These  may  sometimes  eifect  a  repair 
of  an  exposure  of  the  pulp.  This  latter  is  a  physiological  process, 
however,  in  which  the  pulps  of  teeth  are  inclosed  by  further 
deposit  of  calcified  matter,  by  cells  whose  physiological  purpose 
has  been  the  building  of  the  dentin  originally.  Their  sphere  of 
action  is  always  within  the  pulp  chamber,  never  elsewhere.  The 
suggestion  has  been  made  that  some  additions  of  calcium  salts 
may  be  made  on  the  walls  of  the  dentinal  tubules,  narrowing  their 
caliber.  This  is  plausible,  but,  as  yet,  no  sufficient  series  of 
measurements  have  been  made  to  determine  the  facts.  An 
injury  of  any  character  occurring  to  the  dentin  during  its  devel- 
opment remains  an  injury  for  life.  In  the  study  of  atrophy,  we 
find  sheets  of  interglobular  spaces  passing  throughout  that  por- 
tion of  the  dentin  being  formed  at  a  time  of  malnutrition.  These 
are  never  repaired.  They  form  an  injury  that  remains  perma- 
nently. Dentin,  or  enamel,  once  formed,  is  formed  for  all  time ; 
it  never  can  be  re-formed,  changed,  or  improved  in  its  character 
or  qualities.  It  is  fixed  material;  nature  has  furnished  it  with 
no  physiological  means  of  repair  or  betterment. 

Studies  by  Dr.  J.  Leon  Williams. 

ILLUSTRATIONS:    FIGURES  166.158. 

Dr.  J.  Leon  Williams,  of  London,  published  a  series  of 
studies  {Dental  Cosmos,  1897)  of  faults  in  the  teeth  of  animals 
as  compared  with  faults  in  the  teeth  of  man,  and  of  the  beginning 
of  caries  under  plaques  formed  on  the  surfaces  of  teeth,  which 
he  found  to  be  composed  mostly  of  microorganisms  agglutinated 
together.  He  found  the  structure  of  the  human  teeth  much 
more  perfect  than  that  of  the  teeth  of  the  animals.  The  faults 
in  structure  were  less  frequent  in  man  and  generally  of  less  con- 
sequence, notwithstanding  the  fact  that  animals  do  not  suffer 
from  caries  of  the  teeth,  except  in  a  few  rare  instances  of  captive 
animals  kept  in  cages,  some  domesticated  house-dogs,  etc. 


•/   f. 


^ 

/ 

'\ 

FlQ. 

150. 

*<jji^ 


1 


r-^' 


Fig.   156.     A  photomicrograph  of  a  plaque  covering  the  surface  of  the  enamel  in  which  caries  is 
beginning.      Williams. 

FlQ.    157.     A   thick  gelatinoid  plaque  over  the  svirface  of  decaying  enamel.      Williams. 

19 


Fia.  168. 


Fig.  158.  A  photomicrograph  showing  a  stained  film  of  niicroiirganisms  over  the  surface  of  decay- 
ing enamel.  In  pressing  down  the  cover-glass  in  mounting  the  specimen,  the  mierobic  film  has  been 
parted  slightly   from   the  surface  of  the  enamel.      Williams. 


SYSTEMIC    CONDITIONS.  129 

It  will  be  found  by  a  review  of  the  dental  literature,  that 
decay  of  the  teeth  of  man  was  generally  supposed  to  be  because 
of  imperfection  in  their  structure,  and  many  times  it  has  been 
said  that  the  teeth  of  man  were  degenerating  and  were  not  so 
well  calcified  as  the  teeth  of  animals.  After  a  long  series  of 
studies,  Dr.  Williams'  opinion  was  exactly  the  reverse;  and 
further,  that  the  decay  of  the  teeth  of  man  was  not  to  be  attrib- 
uted to  their  faulty  structure.  This  opinion  seems  to  have  been 
well  supported  by  the  histological  structures  developed  by  his 
microscopic  work.  His  work  took  a  wide  range  among  the  lower 
animals. 

As  I  had  been  studying  gelatinous  masses  formed  on  the 
teeth  by  microorganisms  and  their  influence  in  shielding  the 
organisms  growing  in  them  from  washings  by  the  saliva,  which 
would  dissipate  the  acids  formed,  I  was  much  interested  in  this 
phase  of  his  work.  But  later,  in  the  study  of  his  illustrations 
and  methods,  comparing  these  with  my  own  work  along  similar 
lines,  it  seemed  that  he  had  included  all  manner  of  material  that 
contained  microorganisms  (practically  any  material  clinging  to 
the  teeth  contains  them),  going  wide  of  the  line  of  those  forms 
of  fungi  known  to  produce  caries.  He  seems  also  to  have  included 
deposits  through  which  water  would  run  so  easily  that  they 
would  be  no  bar  to  washings  by  the  saliva.  Such  coatings  are 
found  plentifully  over  the  surfaces  of  the  teeth  of  immune  per- 
sons, and  also  in  others  where  there  is  no  decay  of  the  enamel. 
Careful  study  shows  that  many  kinds  of  deposits  upon  the  teeth 
present  similar  appearances,  when  seen  in  microscopic  sections, 
to  those  produced  by  gelatinous  plaques,  and  yet  seem  to  have 
no  influence  whatever  in  the  localization  of  caries.  A  plaque,  to 
have  any  considerable  effect,  certainly  must  have  sufficient  firm- 
ness in  the  moist  state  to  act  more  or  less  perfectly  as  a  dialyzing 
membrane. 

In  the  technical  sense.  Dr.  Williams'  work  was  beautifully 
done,  and  there  is  no  doubt  that  caries  was  shown  under  the 
aggregations  of  organisms  in  many  of  his  photomicrographs. 
Three  of  these.  Figures  156,  157,  158,  are  reproduced  from  the 
Dental  Cosmos,  of  1897,  by  permission. 

SlALO-SEMEIOLOGY. 

Dr.  Joseph  P.  Michaels,  of  Paris,  presented  a  brochure 
under  the  above  title  to  the  International  Dental  Congress, 
Paris,  1900,  which  has  been  translated  into  English  and  published 
in  the  office  of  the  Dental  Cosmos,  1902. 


130  PATHOLOGY    OF    THE    HARD    TISSUES    OP    THE   TEETH. 

In  this,  Dr.  Michaels  claims  to  have  found  the  means  of 
determining  definitely  the  existence  of  the  conditions  of  suscep- 
tibility to,  or  immunity  from,  dental  caries,  by  the  examination 
of  a  few  drops  of  the  individual's  saliva.  Persons  who  have 
spent  some  time  in  Dr.  Michaels'  laboratory  and  looked  over  his 
work,  seem  convinced  that  he  can  do  what  he  asserts.  In  this 
writing,  the  qualities  of  the  saliva  are  summarized  thus:  (1) 
Normal,  (2)  Hypo-acid,  (3)  Hj'per-acid,  and  (4)  Cacochymic. 

In  the  first,  the  normal,  little  or  no  caries  occurs.  In  the 
hypo-acid  condition,  the  susceptibility  is  intense  or  moderate, 
according  to  the  intensity  of  the  condition.  In  the  hyper-acid 
condition  there  is  immunity  from  dental  cai'ies.  The  cacochjTnic 
denotes  a  bad  condition  of  the  saliva,  due  to  some  functional 
derangement  or  organic  disease  without  further  specification,  and 
includes  very  variable  conditions.  It  has  no  special  reference 
to  dental  caries. 

The  terms,  hypo-acid  and  hyper-acid  diathetic  states,  do  not 
refer  to  reactions  to  litmus.  He  says:  "The  abnormal  vital 
processes  tend  in  mankind  to  pathological  conditions,  which  we 
may  classify  under  two  humoral  conditions,  viz.,  hypo-acidity 
and  hyper-acidity.  The  first  state  (lymi^hatism)  is  the  expres- 
sion of  a  vital  over-activity  and  has  as  consequences  the  con- 
tagious diathesis  (scrofula,  tubei'culosis,  syphilis).  The  oxida- 
tions are  over-active  and  the  hj^drations  superior  to  the  normal, 
hence  there  is  a  decrease  in  organic  acidity  and  an  increase  in 
the  saline  chlorids  excreted  by  the  economy.  Hypo-acidity, 
according  to  Duclaux,  favors  chemical  changes  in  the  tissues. 
In  the  hypo-acid  diathesis  all  of  the  oxidations  are  exaggerated 
and  above  normal.  .  .  .  Hyper-acidity  is  a  particular  state 
of  the  oi'ganism  characterized  in  a  general  way  by  slowness  in 
the  biochemical  changes.  .  .  .  It  is  not  doubtful  that  the 
activity  of  caries  in  some  individuals  and  the  immunity  from  or 
tlie  slowness  of  decay  in  others  are  in  correlation  with  diathetic 
states  well  determined,  resulting  from  a  lack  of  proper  balance 
of  the  general  factors,  and  in  particular  of  the  blood  plasma." 

Many  of  the  expressions  in  this  brochure  seem  difficult  for 
many  who  have  read  them  to  understand,  but  it  has  seemed  evi- 
dent that,  while  many  other  substances  in  the  saliva  are  found  to 
influence  conditions  as  to  caries  of  the  teeth,  the  absence  or  pres- 
ence of  the  sulphocyanids,  or  the  large  or  small  proportions 
present,  is  the  most  constant  mark  s(>pnrating  the  condition  of 
susceptibility  to  caries  from  tlie  condition  of  iummnity. 

Much  of  the  work  is  done  by  the  examination  of  crystals  by 


SYSTEMIC    CONDITIONS.  131 

the  microscope  and  micropolariscope,  and  is  necessarily  qualita- 
tive rather  than  quantitative. 

Recently  the  committee  of  the  New  York  State  Dental 
Society  on  dental  science  has  taken  up  the  question  of  the  influ- 
ence of  the  presence  of  the  sulphocyanids  in  the  saliva  as  a 
special  piece  of  work,  and  is  making  numerous  examinations 
by  clinical  and  laboratory  methods.  Its  last  annual  report  is 
not  yet  at  hand,  but  from  the  information  derived  from  private 
sources,  it  seems  that  this  test  alone  is  giving  correct  indications 
as  to  the  susceptibility  to,  or  immunity  from,  caries,  in  about 
ninety-six  to  ninety-seven  per  cent  of  the  individuals  examined. 
This  is  indicated  by  the  absence  of,  or  only  very  slight  reactions, 
indicating  the  presence  of  none  or  a  very  small  quantity  of  the 
sulphocyanids  of  potassium  in  susceptibility,  as  compared  with 
more  decisive  reactions  indicating  a  large  quantity  of  the  sulpho- 
cyanids in  the  saliva  of  immune  persons.  In  the  prosecution  of 
this  work,  another  point  has  developed  which  may  prove  of  much 
significance  upon  further  examination.  In  some  cases  which 
were  examined  a  number  of  times,  the  teeth,  after  being  well 
cleaned,  were  found  again  coated  over  with  gummy  material  so 
quickly  as  to  attract  special  attention.  This  gave  rise  to  the 
suggestion  of  precipitation  from  the  saliva  of  some  material  in 
it  that  was  not  held  in  solution.  Therefore,  this  saliva  was  com- 
pared with  the  saliva  of  others,  in  whom  there  was  an  absence 
of  such  material,  as  to  its  power  of  dissolving  the  residue  of 
saliva  that  had  been  dried.  The  result  was  that  the  saliva  from 
which  such  deposits  occurred  would  not  dissolve  such  residue  at 
all,  while  saliva  from  persons  whose  teeth  remained  free  from 
such  deposits  dissolved  them  readily.  It  will  be  of  much  interest 
to  know  whether  or  not  such  deposits  will  form  films  that  will 
act  as  dialyzing  membranes  and  so  inclose  colonies  of  micro- 
organisms as  to  protect  the  acids  formed  from  a  too  free  dissi- 
pation in  the  fluids  of  the  mouth,  and,  in  this  way,  become  a 
factor  in  the  production  of  the  beginnings  of  caries  of  the 
enamel.  This  may  lead  to  some  important  discoveries  in  the 
near  future. 

Dr.  Carl  Rose,  of  Dresden,  Germany,  is  doing  an  immense 
amount  of  work  on  the  saliva,  especially  with  reference  to  its 
amount  under  different  conditions  of  living  and  the  variations 
in  the  salts  it  contains.  In  this  work  he  is  collecting  an  immense 
amount  of  data  with  reference  to  the  effects  of  the  salts  found 
in  the  water  used  for  drinking  and  cooking  purposes.  In  this 
work  he  is  developing  important  facts  regarding  the  relation  of 


132  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE    TEETH. 

these  salts  to  the  percentage  of  dental  caries,  the  relation  of  the 
amount  of  saliva  secreted  by  the  person  to  the  percentage  of 
caries,  the  relation  of  salts  in  drinking  water  to  the  development 
of  the  salivary  glands,  etc.  The  examinations  have  been  mostly 
made  in  children.  These  have  been  widely  distributed  in  Ger- 
many, Switzerland,  Denmark,  Sweden,  etc.  The  work  is  still 
in  progress. 

This  mention  of  work  being  done  is  given  here  to  show  the 
direction  which  thought  is  taking  and  the  activity  manifested, 
rather  than  for  the  purpose  of  giving  specific  information  of  its 
detail.  The  questions  are  of  very  recent  origin.  The  question 
of  immunity  and  susceptibility  to  dental  caries  as  a  systemic  con- 
dition as  known  to-day,  was  first  propounded  in  1895.  Years 
will  probably  be  reqi;ired  before  this  problem,  involved  in  such 
obscurity  and  difficulty,  can  be  so  unfolded  and  simplified  that 
the  general  profession  may  make  practical  use  of  it  in  the  treat- 
ment of  dental  caries.  In  the  meantime,  the  general  discussion 
of  it  belongs  to  the  journal  literature  rather  than  to  books. 

The  Saliva. 

Wlien  the  saliva  is  mentioned  without  designation  of  its 
special  parts,  it  is  most  generally  understood  that  the  mixed 
fluid  found  in  the  mouth  is  meant.  This  is  made  up  of  secretions 
from  several  sources,  any  of  which  may  be  examined  separately. 
These  are  the  saliva  from  the  parotid  gland,  saliva  from  the 
submaxillary  and  sublingual  glands,  and  mucus  from  the  mucous 
follicles  situated  in  the  mucous  membrane  of  the  mouth.  The 
different  salivas  are  much  alike.  Though  variable,  they  are 
generally  very  limpid,  watery  secretions.  The  mucus,  on  the 
other  hand,  is  more  generally  found  to  be  a  thick,  ropy  secretion. 
If  the  parotid  saliva  is  collected  directly  from  Stenson's  duct 
it  will  generally  be  found  to  be  about  neutral  in  its  reaction  with 
litmus,  varying  from  slightly  alkaline  to  slightly  acid.  If  the 
mucous  membrane  of  the  mouth,  say  the  roof  of  the  mouth,  is 
dried  and  the  mouth  held  open  for  some  time,  one  will  generally 
find  here  and  there  globules  of  fluid  collecting  on  its  surface. 
Sometimes  many  of  these  will  be  seen ;  sometimes  very  few,  and, 
occasionally,  none  without  a  very  long  wait.  The  secretion  seems 
to  be  very  variable.  Touching  litmus  to  this  generally  brings  a 
very  definite  acid  reaction.  In  the  lips,  I  have  usually  found 
much  larger  glands  than  elsewhere  in  the  mucous  membrane. 
Some  of  the  larger  of  these  seem  to  emit  a  much  more  watery 
fluid  than  the  usual  submucous  glands.    It  is  more  of  the  nature 


THE    SALIVA.  133 

of  that  from  the  salivary  glands.  This  seems  to  have  to  do  with 
the  moistening  of  the  mucous  membrane  of  the  lips  especially. 
The  mucus  is  very  variable,  both  in  amount  and  consistence. 
Often  it  is  very  thick  and  viscous^  so  mucli  so  that,  by  touching 
the  finger  to  a  globule,  it  may  be  drawn  out  into  a  very  long 
thread. 

The  variations  in  the  viscosity  of  the  general  saliva  have 
been  commented  upon  by  most  of  those  who  have  examined  it  in 
many  individuals.  Often  it  is  found  to  be  very  thin  and  watery. 
Not  very  infrequently  it  is  almost  as  thick  and  viscous  as  the 
mucus  itself.  I  have  met  with  persons  whose  saliva  was  so 
viscous  that  I  could  at  any  time  draw  out  threads  two  or  three 
feet  long  by  touching  my  finger  to  it  and  drawing  it  away.  In 
filtering  this,  it  will  leave  an  unusually  large  amount  of  gummy 
material  on  the  filter.  In  such  cases  an  excitation  of  the  flow  of 
saliva  generally  causes  the  thinning  of  the  mixed  fluid  for  the 
time,  which  seems  to  be  due  to  the  larger  proportion  of  the 
parotid,  submaxillary  and  sublingual  salivas. 

There  are  great  differences  in  the  saliva  as  to  deposits. 
Many  persons  are  found  whose  teeth  are  free  from  deposits 
of  gummy  or  slimy  material.  The  saliva  seems  to  hold  all  of  its 
ingredients  in  complete  solution,  and  is  capable  of  dissolving 
quickly  all  of  the  ordinarily  soluble  things  with  which  it  comes 
in  contact.  Therefore,  the  mouth  is  always  clean  and  free  from 
debris.  In  others  the  saliva  seems  habitually  incapable  of  hold- 
ing its  own  ingredients  in  solution.  The  teeth  especially  are 
continually  covered  with  a  slimy,  viscid  coating,  and  more  solid 
deposits  are  frequently  found.  Many  writers  have  noted  these 
differences  in  persons,  and  also  at  different  times  in  the  same 
individuals. 

The  salts  of  the  saliva  seem  to  be  very  variable.  If  a  person 
consults  many  authors,  who  have  rei^orted  their  findings,  he  is 
soon  lost  in  a  maze  of  discrepancies.  Dr.  Michaels  quotes  the 
following  from  Hammerbacher  as  representing  normal  saliva  in 
an  analysis  of  1,000  parts  =  o  if  . 

Water   994.203         Carbonates 

Mucin  2.202         Phosphates 

Ptyalin 1.390         Chlorids 2.205 

Fixed  constituents  . .     5.790         Sulphates 

Nitrates 


In  normal  and  abnormal  salivas,  somebody  has  found  ahnost 
every  normal,  abnormal  and  accidental  constituent  of  the  body. 


134  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE   TEETH. 

Some  seem  to  be  of  the  opinion  that  much  of  the  make-up  of 
the  saliva  is  a  transudation  from  the  blood,  of  constituents  that 
it  may  happen  to  contain  at  the  time,  together  with  some  con- 
stituents that  are  characteristic  of  this  fluid.  It  seems  to  be  on 
this  idea  that  Dr.  Michaels  bases  the  proposition  that  in  the 
saliva  an  index  is  to  be  found  of  the  general  and  special  bodily 
conditions,  when  one  has  learned  to  read  them.  For  the  present 
I  must  conclude  that  the  finer  pathological  reading  of  the  indi- 
cations given  by  this  fluid  are  in  a  chaotic  state ;  that  only  a  few 
things  are  assuming  definiteness  and  that  much  time  will  yet  be 
necessary  to  unravel  its  complexities. 

ACIDITY    OF    THE    SALIVA. 

The  question  of  the  reaction  of  the  saliva  has  been  under 
especial  discussion  for  a  century,  and  still  men  are  differing  so 
widely  as  to  their  findings  that  quotations  would  lead  to  confu- 
sion. My  own  conclusion,  after  many  examinations,  is  that  the 
saliva  as  it  comes  from  the  glands  is  very  nearly  neutral,  but 
varies  within  a  rather  narrow  range  from  alkaline  to  acid.  On 
account  of  the  acidity  of  the  mucus,  the  mixed  fluid  is  generally 
slightly  acid.  This  becomes  more  decisively  acid  by  the  fermen- 
tation jjrocesses  of  the  microorganisms  that  are  continuously 
growing  in  the  secretions  in  the  mouth.  Some  of  the  elements  of 
the  saliva  seem  to  be  fermentable,  and  sugars  and  starches  taken 
into  the  mouth  quickly  become  fermentable.  If  examined  in  the 
early  morning  at  the  time  of  rising  from  bed,  the  saliva  will,  as 
the  general  rule,  redden  litmus  sharply.  If  examined  after  break- 
fast, the  acidity  is  much  reduced.  The  acidity  will  then  increase 
until  the  next  meal  time,  after  which  it  will  be  reduced  again. 
This  is  being  continually  repeated.  When  the  flow  of  saliva  is 
least,  as  in  sleep,  its  acidity  is  increased  by  the  fermentative 
processes  of  the  microorganisms  growing  in  it.  At  meal  time 
fresh  saliva  is  secreted  in  larger  quantities,  and  this,  with  the 
food,  carries  the  superacidulated  saliva  away,  replacing  it  with 
that  which  is  normal.  The  degree  of  acidity  may  depend  in  some 
part  upon  the  differences  in  the  saliva  as  it  comes  from  the 
glands.  But,  from  my  own  examinations,  the  evidence  seems  to 
point  especially  to  ditferences  in  the  fermentation  going  on  in  the 
mouth.  Differences  in  the  constitution  of  the  saliva  —  probably 
in  its  salts,  possibly  other  matters  also  —  seem  to  render  decora- 
positions  by  microorganisms  much  more  rapid  in  some  than  in 
others.    Again,  the  complexities  of  the  saprophitic  organisms  in 


THE    SALIVA.  135 

the  saliva,  are  matters  of  time,  place  and  the  prevalence  of  spe- 
cial forms  of  these  growths  in  the  surroundings. 

Under  the  idea  that  caries  of  the  teeth  was  caused  by  acidity 
of  the  saliva,  this  subject  has,  in  the  past,  been  regarded  as  very 
important.  I  do  not  now  so  consider  it.  Acidity  of  the  general 
saliva  does  not  become  sufficient  to  cause  caries.  Those  immune 
to  caries  have  saliva  fully  as  acid  as  those  most  intensely  sus- 
ceptible to  caries.  The  two  seem  not  at  all  related  as  cause 
and  effect.  Microorganisms  produce  caries  only  when  they  are 
secluded  from  the  general  saliva  by  some  kind  of  covering,  as 
has  been  sufficiently  indicated  on  previous  pages.  Conditions  of 
the  saliva  that  enable  microorganisms  to  form  these  coverings, 
or  which  form  them  independently  of  the  action  of  microorgan- 
isms, are,  apparently,  the  important  objects  of  search.  It  is  in 
no  proper  sense  a  search  for  conditions  in  which  microorganisms 
will  or  will  not  grow  in  the  saliva.  They  grow  in  all  conditions 
yet  found,  and  just  as  freely  in  the  saliva  of  immune  persons  as 
in  the  saliva  of  the  most  susceptible. 

VISCOSITY    OF    THE    SALIVA. 

If  the  conditions  of  the  fluids  of  the  mouth  be  studied  from 
week  to  week,  in  each  of  a  considerable  number  of  persons  with 
reference  to  accumulations  on  the  teeth,  it  will  be  found  that 
the  saliva  of  some  persons  is  habitually  very  thin  and  watery, 
and  that  the  teeth  are  habitually  clean.  The  saliva  of  other  per- 
sons will  be  thicker  and  more  viscous.  This  latter  may  be  drawn 
out  into  long  threads  by  touching  the  finger  to  it  and  drawing  it. 
This  has  been  termed  "ropy  saliva"  or  "viscous  saliva."  Gen- 
erally the  teeth  will  be  difficult  to  keep  clean  when  the  saliva  is 
ropy.  The  person  may,  by  care,  keep  the  teeth  looking  well,  but 
a  close  examination  will  show  them  to  be  covered  by  a  trans- 
parent slimy  material  of  sufficient  thickness  to  be  clearly  appar- 
ent. If  this  be  cleaned  away,  a  new  deposit  will  be  found  the 
next  day.  In  many  of  these  cases,  if  the  saliva  be  touched  by  a 
rapidly  rotating  disk  or  stone,  it  will  quickly  thicken  up  into  a 
more  or  less  firm  coagulum  around  the  disk  or  stone,  reminding 
one  of  the  clotting  of  fibrin.  The  opportunity  to  observe  this 
can  be  best  obtained  by  holding  the  buccal  mucous  membrane 
well  away  from  the  lower  bicuspids  and  molars  with  one  finger 
and  waiting  a  little  for  some  accumulation  of  saliva  and  then 
touching  the  margin  of  the  rapidly  rotating  disk  or  stone  to  the 
surface  of  this  accumulation.    Often  the  saliva  will  quickly  ball 


136  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

up  on  the  disk  or  stone  in  a  clot  of  considerable  firmness.  The 
degree  of  stickiness  of  this  mass  and  the  firmness  of  the  clot 
formed  is  perhaps  the  best  index  to  the  degree  of  ropiness  of 
the  saliva.  In  some  individuals  this  ropiness  will  be  very  marked 
at  each  examination  for  months  and  years  together,  but  will 
differ  in  degree  from  time  to  time.  This  test,  when  applied  to  a 
number  of  individuals,  will  give  a  very  marked  contrast  between 
those  with  thin,  watery  saliva  and  those  with  ropy  saliva,  and 
will  show  all  manner  of  gradations  between  the  extremes.  Wliile 
the  degree  of  ropiness  of  the  saliva  is  not  a  certain  index  to  the 
degree  of  susceptibility  to  dental  caries  in  the  person,  it  will 
almost  uniformly  be  found  that  caries  occurring  in  the  presence 
of  this  condition  will  be  more  difficult  of  management  than  when 
occurring  in  similar  degree  in  persons  with  thin,  watery  saliva. 
Proximal  cavities,  particularly,  will  more  certainly  spread 
broadly  bucco-lingually,  and  deposits  on  fillings  will  be  more 
likely  to  overstep  the  margins  and  cause  recurrence  of  decay. 
Therefore,  decay  is  much  more  likely  to  recur  after  fillings  have 
been  made. 

GLUTINOUS   DEPOSITS   FROM    THE    SALIVA. 

Another  condition  not  frequently  noted  by  writers,  but  one 
to  which  my  attention  has  been  strongly  drawn  clinically,  is  the 
tendency  to  slimy  or  glutinous  coatings  upon  the  teeth  of  some 
persons,  which,  apparently,  is  a  deposit  from  the  saliva.  These 
deposits  may  be  found  especially  upon  the  axial  surfaces  of  the 
teeth.  They  also  tend  to  keep  the  mucous  membranes  slimy  and 
slippery  to  the  touch.  There  is  also  a  degree  of  viscosity  clearly 
discoverable  by  rubbing  buccal  surfaces  of  the  teeth  back  and 
forth  a  few  times  with  the  finger  and  then  rubbing  this  material 
between  the  finger  and  thumb.  This  seems,  often,  to  be  inde- 
pendent of  any  considerable  ropiness  of  the  saliva.  It  seems  to 
be  a  deposit  from  the  saliva  of  a  material  which  it  fails  to  hold 
in  solution.  I  have  supposed  this  deposit  to  consist  chiefly  of 
mucin,  but  I  know  of  no  examinations  that  certainly  indicate  its 
nature.  It  is  different  entirely  from  the  material  foi'ming  the 
gelatinoid  plaques.  It  is  apparently  not  formed  under  the  influ- 
ence of  microorganisms,  or,  if  so,  it  is  through  their  influence  on 
the  saliva  as  a  body. 

A  very  curious  and  possibly  important  discovery  has  been 
made  by  the  committee  of  the  New  York  State  Dental  Society 
on  dental  science,  alluded  to  previously,  which  may  be  thus 


THE   SALIVA.  137 

stated.  The  deposit  is  insoluble  in  the  saliva  of  the  person  in 
whose  mouth  it  is  found,  but  is  readily  soluble  in  the  saliva  of 
persons  in  whose  mouths  such  deposit  is  not  found.  From  recent 
examinations,  I  have  been  led  to  strongly  suspect  that  this  may 
favor  the  beginning  of  caries  or  actually  furnish  one  of  the  neces- 
sary elements,  by  affording  coverings  that  will  shield  micro- 
organisms and  their  acid  products  from  washings  by  the  saliva ; 
but,  as  yet,  this  is  by  no  means  assured.  This  condition  seems 
to  be  much  less  constant  in  the  mouth  of  an  individual  than  ropy 
saliva. 

The  conditions  in  which  solid  deposits  from  the  saliva  occur, 
as  salivary  calculus,  are,  of  course,  well  known  from  observation 
of  results.  As  a  rule,  this  condition  belongs  to  immune  persons 
or  those  who  would  have  become  immune  if  caries  had  been  kept 
under  control.  It  used  to  be  a  saying  that  diseases  of  the  gums 
from  deposits  of  calculus  destroyed  the  best  dentures,  that  is, 
teeth  that  did  not  decay.  In  these  later  days  we  are  often  finding 
dentures  destroyed  from  this  cause  after  caries  had  been  con- 
trolled with  much  difficulty  up  to  the  time  when  immimity  to 
decay  had  given  relief.  Some  cases  of  extensive  deposits  of 
calculus  occur,  however,  coincidently  with  rapidly  progressive 
decay  of  the  teeth. 

There  is  to-day  no  more  promising  field  of  useful  discovery 
than  in  qualitative  examinations  of  the  saliva  recorded  with 
intelligently  observed  conditions  of  the  mouth  and  teeth.  All 
the  aids  that  scientific  instruments  can  give  should  be  brought 
to  bear  to  bring  out  the  details  of  its  chemical  constituents. 

SIGNS    OF    SUSCEPTIBILITY    AND    IMMUNITY    TO    DENTAL    CAEIES. 

In  the  meantime,  the  recognition  of  the  conditions  of  sus- 
ceptibility and  of  immunity,  and  the  more  prominent  symptoms 
by  which  these  may  be  known,  becomes  important.  As  yet,  no 
language  expression  regarding  this  has  taken  such  form  that 
the  conditions  may  be  readily  conveyed  in  words.  I  suppose  that 
most  dentists  at  present  wait  for  the  disappearance  of  superficial 
beginnings  of  decay  before  announcing  the  coming  of  immunity 
to  caries,  but  those  who  are  accustomed  to  looking  for  signs  of 
the  coming  of  immunity  to  the  beginnings  of  decay  depend  more 
upon  other  conditions  that  may  be  seen  earlier ;  which  point  out 
the  approach  of  the  condition  of  immunity,  or  a  condition  in 
which  the  predisposition  to  caries  is  abating.  These  signs  are 
practically  the  same  as  formerly  relied  upon  for  determining  the 
condition  of  hard  teeth  as  distinguished  from  soft  teeth.    While 


138  PATHOLOGY    OF    THE    HABD    TISSUES   OF    THE    TEETH. 

this  interpretation  was  wrong,  the  appearances  pointed  out  those 
conditions  in  which  little  or  no  decay  occurred,  as  distinguished 
from  conditions  of  marked  susceptibility  to  decay.  The  observa- 
tions as  to  the  liability  of  the  person  to  caries  were  correct,  as 
most  of  the  older  men  can  testify  from  long  experience;  yet  I 
think  that  there  will  not  be  a  very  close  agreement  among  men 
if  different  persons  undertake  to  put  these  signs  into  word  forms. 
The  assemblage  of  differences  in  the  things  seen  is  difficult  to 
form  into  language.  It  is  much  like  the  remark  an  old  and  very 
skillful  physician  made  in  speaking  of  the  difificulties  of  young 
men  in  medicine, ' '  The  best  asset  is  the  ability  to  read  the  physi- 
cal expression  of  disease,  which  is  acquired  only  by  much  careful 
observation."  This  physical  expression  of  the  assemblage  of 
conditions  in  immunity  is  such  as  gives  the  impression  of  solidity 
and  firmness  to  the  denture.  There  is  a  slight  darkening  of  the 
teeth  without  uncleanness.  Especially  there  is  more  apt  to  be  a 
gathering  of  dark  color  here  and  there  instead  of  lodgments  of  a 
lighter  shade.  However,  until  some  more  apt  expression  of  this 
in  words  arises,  which  will  appeal  to  many  persons  as  having 
weight,  any  considerable  discussion  of  it  will  be  of  little  value. 
We  can  certainly  recognize  it  by  the  fact  that  new  beginnings  of 
decay  cease  to  api^ear.  Gradually  the  assemblage  of  appearances 
which  foretell  the  coming  of  this  will  be  recognized.  These  dif- 
ferences are  evidently  due  to  changes  in  the  constitution  of  the 
saliva. 

MiCKOOKGANISMS   OF    THE    MoUTH. 

It  is  not  the  intention  to  enter  into  any  lengthy  discussion 
of  the  microorganisms  of  the  mouth.  That  subject  should  be 
studied  in  the  bacteriological  laboratory.  It  may  be  well,  how- 
ever, to  mention  here  that  the  numbers  of  species  of  microorgan- 
isms habitually  growing  in  the  saliva,  as  mouth  organisms,  seem 
to  have  been  greatly  exaggerated.  The  fact  is,  the  human  saliva 
becomes  a  harbor  for  any  and  all  microorganisms  floating  in  the 
atmosphere,  or  introduced  with  food,  and  many  of  these  will 
grow  for  a  little  while  in  the  saliva,  or  will  grow  in  culture  media 
when  removed  from  the  saliva.  These  strangers  are  always 
being  caught  up  by  persons  who  cultivate  microorganisms  from 
the  saliva.  In  the  culture  media  used,  many  of  them  grow  very 
much  better  than  the  mouth  organisms  proper  and  form  mucli 
more  attractive  growths.  A  number  of  men  have  given  large 
numbers  of  species  of  microorganisms  as  found  in  the  saliva, 
but  they  seem  not  to  have  undertaken  the  work  of  determining 


MICROORGANISMS    OF    THE    MOUTH.  139 

what  organisms  are  habitually  found  in  the  mouth  and  separat- 
ing these  from  the  occasional  or  frequent  visitors  there.  These 
visitors  are  of  no  consequence  to  us,  except  as  they  happen  to 
be  pathogenic  in  character.    The  great  bulk  of  them  are  harmless. 

At  one  time,  when  I  was  studying  this  subject,  I  found  that 
very  much  dreaded  organism,  streptococcus  pyogenes,  in  the 
saliva  and  under  the  finger  nails  of  six  nurses  in  a  hospital  ward. 
All  of  them  had  been  engaged  more  or  less  closely  in  the  handling 
of  suppurations  in  which  this  organism  was  the  principal  factor, 
and,  of  course,  would  have  been  in  serious  danger  from  any 
lesions  that  would  have  allowed  the  organisms  to  enter  their 
tissue.  From  observations  made  at  the  time,  it  was  my  belief 
that  they  had  infected  some  operation  wounds  that  otherwise 
would  have  escaped  infection.  A  week  later  I  was  unable  to  find 
any  trace  of  these  organisms  in  the  saliva  of  these  persons. 

I  have  cultivated  microorganisms  from  the  mouth  in  several 
different  cities  and  noted  particularly  the  varieties  found.  Fur- 
ther, I  have  compared  cultivations  annually  for  many  years  with 
a  view  of,  in  some  degree,  separating  the  regular  habitues  of 
the  saliva  from  those  organisms  that  grow  accidentally,  or  are 
caught  in  the  mouth,  but  do  not  belong  there.  As  a  matter  of 
fact,  the  great  bulk  of  microorganisms  found  in  the  mouth  are 
there  by  accident,  and  yet  it  requires  very  persistent  work  to 
separate  them  from  the  regular  habitues  of  the  mouth. 

In  1891  and  1892,  in  Chicago,  I  found  rather  a  large  bacillus 
growing  in  chains  that  stained  in  distinct  lines,  running  diago- 
nally around  each,  other  parts  of  the  cell  not  taking  the  stain. 
This  made  a  very  beautiful  appearance  as  a  mounted  specimen. 
It  occurred  in  almost  every  mouth  examined,  both  among  stu- 
dents and  patients  in  the  infirmary,  and  it  continued  during 
these  two  years.     The  next  year,  however,  it  had  disappeared. 

By  this  method  of  elimination,  I  have  reduced  mouth  micro- 
organisms proper  —  those  that  are  found  in  practically  every 
mouth,  either  in  children  or  grown-up  people,  in  which  there  are 
some  differences  —  to  about  twelve  or  fourteen  varieties,  cer- 
tainly not  more  than  fourteen.  Of  these,  only  about  one-half  can 
be  cultivated  in  artificial  media. 

By  far  the  most  important  of  these  that  I  have  ever  exam- 
ined carefully,  and  the  one  that  is  found  in  every  mouth,  is  the 
streptococcus  media,  streptococcus  buccalis,  or  caries  fungus. 
This  is  in  the  saliva  of  young  children,  and  in  old  people,  and  all 
ages  between.  A  short  bacillus  that  was  seen  and  described  by 
Dr.  Miller,  but  not  named  by  him,  which  I  have  called  bacillus 


140  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE    TEETH. 

alba,  because  of  its  white  color  in  growths  upon  gelatin  or  upon 
agar-agar,  is  a  persistent  inhabitant  of  the  human  mouth.  That 
which  I  have  termed  a  zigzag  coccus  is  also  very  generally  found, 
and  often  it  may  be  found  very  deep  in  carious  dentin.  It  is  a 
staphylococcus,  liquefies  gelatin  readily  and  is  often  found  in 
alveolar  abscess.  The  familiar  tetragenous  is  sometimes  miss- 
ing, but  is  very  usually  found  by  a  little  search  in  the  mouths  of 
young  people.  Another  organism,  that  I  have  called  micrococcus 
irregularis,  because  of  the  irregular  size  and  foi'm  of  the  indi- 
vidual cocci,  is  sometimes  pretty  hard  to  find,  but  is  generally 
found.    Dr.  Miller  describes  this  also,  but  gives  it  no  name. 

Other  organisms  habitually  found  in  the  mouth  are  all  of 
the  non-cultivatable  varieties,  the  most  prominent  among  which 
is  leptothrix  buccalis  —  the  soft  threads  —  and  the  leptothrix  of 
Vignon  —  the  stiff  threads  —  that  often,  under  the  microscope, 
look  almost  like  so  much  hay.  This  later  organism  I  have  suc- 
ceeded in  cultivating  through  three  generations,  and  find  that  it 
runs  through  three  forms:  A  straight  stiff  stem,  which  finally 
breaks  up  into  bacilli,  which,  in  turn,  give  rise  to  spores,  which 
appear  as  cocci  in  stale  cultures.  These  have  grown  and  run 
through  a  similar  change,  running  to  the  third  generation,  but 
I  could  not  proceed  further  with  artificial  culture.  It  is  very  dif- 
ficult to  isolate,  for  the  reason  that  it  does  not  form  colonies  on 
gelatin  or  agar-agar. 

The  streptococcus  continuosum,  which,  when  the  threads 
are  broken  up,  has  often  been  confounded  with  the  caries  fungus, 
is  occasionally  seen  in  broth  cultures  in  isolated  threads.  A  few 
times  I  have  succeeded  in  isolating  it  and  getting  a  pure  growth, 
but  could  not  grow  it  a  second  time  from  such  cultures.  The 
growth,  when  pure,  is  in  great  festoons  that  will  fill  the  whole 
tube  for  a  space,  while  the  broth  shows  none  of  the  cloudiness 
usually  found  when  microorganisms  are  growing.  These  fes- 
toons are  almost  a  pure  white.  As  it  will  not  form  colonies  on 
either  gelatin  or  agar-agar,  it  is  extremely  difScult  to  isolate. 

Another,  of  very  peculiar  form,  is  the  micrococcus  vaginatus, 
described  by  Dr.  Miller,  which  refuses  all  of  the  anilin  dyes,  and 
thus  far  can  be  stained  only  with  iodin  dissolved  in  a  solution 
of  potassium  iodid.  This  organism  may  usually  be  found  with- 
out difficulty  about  the  necks  of  the  teeth,  wherever  there  is  a 
little  accumulation,  if  properly  looked  for,  using  iodin  stains. 
Otherwise,  they  are  not  seen,  though  they  may  be  plentiful  in 
smear  preparations.    They  have  never  been  cultivated. 

These,  with  the  varieties  of  the  threadlike  forms,  do  not 


MICROOKGANISMS    OF    THE    MOUTH.  141 

grow  in  any  culture  media.  These  latter  may  be  seen  in  active 
motion  in  saliva  taken  from  almost  any  part  of  the  mouth  when 
a  drop  is  covered  simply  with  a  cover-glass  without  other  prep- 
aration. 

This  forms  about  a  complete  list  of  the  microorganisms 
found  sufficiently  constant  in  the  saliva  to  regard  them  as  regu- 
lar dwellers  in  the  mouth.  We  know  very  little  of  the  functions 
of  these  uncultivatable  varieties.  So  far  as  we  are  now  able  to 
judge  from  clinical  observation,  they  are  of  no  especial  conse- 
quence. The  microorganisms  which  produce  putrid  decomposi- 
tion, so  frequently  found  in  the  mouth,  are  there  by  accident,  if 
we  may  term  it  such,  for  they  are  apparently  always  on  hand, 
wherever  there  is  a  material  for  putrid  decomposition  in  the 
mouth  or  elsewhere.  To  produce  true  putrefaction,  they  must 
be  in  a  position  of  complete  exclusion  of  oxygen.  There  are, 
however,  decompositions  closely  resembling  true  putrefaction, 
which  occur  without  complete  exclusion  of  oxygen. 

Note. —  In  recent  years  some  thread  forms  of  microorganisms  of  the  mouth  have 
been  cnltivated  and  the  effort  made  to  show  them  to  l>e  of  pathological  importance. 
In  an  article  in  the  Monatsschrift  fiir  ZahnheiUciinde,  1909,  page  24,  there  is  an  article 
by  Zahnarzt  E.  Paul,  of  Dresden,  which  gives  a  bibliography  of  articles  on  this  subject. 


142  PATHOLOGY    OF    THE    HABD    TISSUES    OF    THE    TEETH. 


UTILITY  OF  STUDIES  OF  DENTAL  CARIES. 

When  Dr.  Miller  made  out  the  life  history  of  the  micro- 
organisms which  cause  caries  of  the  teeth  and  fully  determined 
their  action  in  carious  dentin,  it  was  hoped  by  many  that  this 
would  be  a  guide  to  treatment  that  would  become  of  great  advan- 
tage in  the  practice  of  dentistry.  The  profession  did  not  appre- 
ciate the  wide  difference  between  caries  of  dentin  and  caries  of 
enamel,  and  did  not  realize  the  greater  importance  of  an  undei'- 
standing  of  caries  of  enamel  —  which  is  necessarily  the  first  tis- 
sue involved  in  dental  caries  —  in  the  practical  application  of 
filling  operations  for  the  control  of  caries.  The  importance  of 
this  factor  in  the  practical  use  of  Dr.  Miller's  findings  in  the 
treatment  of  dental  caries  has  come  very  slowly  to  the  minds  of 
men ;  but  it  must  now  be  seen  that  these  findings  have  been  the 
basis  of  advancement  in  the  study  of  caries  of  enamel,  which 
has  directed  the  formulation  of  our  principles  of  treatment.  The 
interpretation  which  held  that  the  teeth  decayed  because  of  inher- 
ent weakness  in  the  teeth  themselves,  or  from  variations  in  their 
calcium  salts,  seems  to  have  been  responsible  for  much  of  this 
delay.  The  profession  has  been  very  slow  to  understand  that 
caries  of  the  enamel  is  the  principal  factor  to  be  considered  in 
any  treatment  that  may  be  instituted  for  the  control  of  dental 
caries.  We  can  not  prevent  the  growth  of  microorganisms  in  the 
saliva,  as  has  been  determined  by  Dr.  Miller  and  confirmed  by 
numbers  of  men;  therefore  our  attention  must,  for  the  present, 
be  turned  to  the  question  of  preventing  or  limiting  the  injuries 
they  do  to  the  teeth. 

Caries  of  enamel  is  the  initial  lesion  and  always  occurs  as 
the  beginning  process  of  dental  caries.  When  the  enamel  has 
been  penetrated  and  the  carious  process  becomes  established  in 
the  dentin,  the  only  possible  method  of  treatment  is  by  its  eradi- 
cation by  excavation  and  filling.  In  caries  of  dentin,  the  micro- 
organisms have  become  established  within  the  tissue  itself  and 
can  not  be  reached  by  any  antiseptic  or  prophylactic  measures. 
Caries  of  enamel,  however,  always  begins  upon  the  outside  of 
the  tooth,  or  in  pits  and  fissures  in  the  surface,  most  of  which  are 
readily  reached  by  careful  cleaning  and  are  amenable  to  prophy- 
lactic measures,  when  these  can  be  applied  with  sufficient  fre- 
quency.    This,  however,  as  to  frequency,  seems  very  nearly 


UTILITY   OF   STUDIES   OF  DENTAL   CAEIES.  143 

impossible  in  all  of  those  positions  which  patients  can  not  them- 
selves successfully  reach. 

The  work  that  I  have  myself  done  in  the  prophylactic  treat- 
ment of  buccal  surfaces  shows  plainly  that  decay  of  these  can  be 
perfectly  controlled  by  the  use  of  the  tooth  brush  and  plain  water 
by  the  patient,  whenever  the  habit  is  sufficiently  formed  that  it 
will  not  be  neglected.  The  principal  utility  in  sight  just  at  the 
present  time  in  the  study  of  caries  of  enamel  is  that,  by  these 
studies,  one  will  learn  to  apply  extension  for  prevention  logi- 
cally to  the  cases  that  present,  and  will  not  make  the  mistake  of 
cutting  too  wide  or  of  cutting  too  little,  so  frequently  as  is  being 
done  now  by  men  in  dental  practice.  The  indications  are  suffi- 
ciently plain  to  those  who  know  them. 

It  seems  to  me  that  these  principles  have  been  described 
with  sufficient  accuracy  for  all  men  to  learn  them.  To  make 
these  descriptions  better  and  plainer  is  one  of  the  objects  in  writ- 
ing this  book.  Heretofore  they  have  never  been  illustrated  as 
we  are  able  to  illustrate  them  now.  The  idea  that  dental  practice 
is  purely  mechanical  and  not  dependent  upon  knowledge  of  the 
pathology  of  dental  caries,  should  be  abandoned  forever.  To 
learn  to  use  instruments  deftly  and  to  make  an  excellent  filling 
from  the  mechanical  standpoint  is  essential,  and  it  is  well  that 
so  many  persons  are  becoming  able  to  do  this,  but  it  is  not  enough 
to  make  a  splendid  filling  from  a  mechanical  standpoint.  The 
planning  of  the  filling  must  be  such  as  to  adapt  it,  not  only  to 
the  cure  of  the  particular  decay,  but  to  prevent  the  recurrence 
of  caries  in  the  future. 

To  do  this  wisely  requires  a  closer  study  of  the  beginnings 
of  dental  caries  in  the  enamel  than  has  yet  been  made  by  the 
general  body  of  the  profession.  When  this  has  been  accomplished 
and  the  better  knowledge  of  these  processes  has  become  gener- 
ally diffused,  the  treatment  of  dental  caries  will  be  far  more  suc- 
cessful than  it  is  to-day.  The  dentists  of  the  future  must  have 
this  information.  The  prophylactic  treatment,  or  systematized 
cleaning,  for  prevention  of  caries  of  the  teeth,  which  is  claiming 
attention  just  now,  can  not  be  wisely  done  without  a  closer  study 
of  the  conditions  that  cause  the  beginnings  and  the  localizations 
of  decay,  and  of  the  signs  of  susceptibility  and  immunity.  The 
existence  of  these  later  conditions,  as  now  understood,  has  been 
recognized  so  recently  that,  as  yet,  no  common  technical  language 
has  been  developed  by  which  the  symptoms  of  coming  immunity 
can  be  adequately  described.  Indications  are  pointing,  however, 
to  means  of  doing  this  in  the  early  future  which  will  give  a  more 


144  PATHOLOGY   OF    THE    HAKD    TISSUES    OP    THE    TEETH. 

definite  phase  to  prophylaxis  as  applied  to  dental  caries.  The 
complete  divorcement  of  dental  practice  from  studies  of  the 
pathology  of  dental  caries,  which  has  existed  in  the  past,  is  an 
anomaly  in  science  that  should  not  continue.  It  has  the  tendency 
plainly  apparent  to  make  dentists  mechanics  only. 

Vital  Phenomena  in  Cakies. 

ILLUSTRATIONS:    FIGUEES  159-161. 

Because  of  the  fact  that  the  teeth  are  vital,  it  has  been  con- 
tended that  vital  influences  play  a  very  important  part  in  caries. 
This  idea,  however,  has  been  gradually  disappearing  for  the  last 
seventy-five  years,  and  but  little  of  it  is  seen  in  our  literature  of 
to-day.  We  must  not  conclude  from  this  that  the  teeth  are  not 
vital,  that  they  are  not  living  tissue.  Teeth  that  have  lost  their 
pulps,  the  dentin  of  which  has  lost  its  vitality,  decay  the  same 
as  teeth  with  living  dentin.  This  was  disputed  for  many  years, 
and  the  opinion  asserted  that  the  decay  in  teeth  that  had  lost 
their  pulps  was  of  a  different  character  from  that  occurring  in 
teeth  with  living  pulps.  This  also  has  been  definitely  given  up 
and  has  disappeared  from  the  recent  literature.  To-day,  the 
vitality  of  the  teeth  is  not  regarded  as  influencing  caries  in  any 
considerable  degree.  Caries  progresses  the  same  in  teeth  with 
living  pulps  as  in  teeth  with  dead  pulps.  Some  thought  decay 
was  more  rapid  in  teeth  with  dead  pulps,  others  have  disputed  it ; 
certainly  there  is  no  difference  worth  contention. 

Generally,  caries  of  the  teeth  progresses  without  pain  until 
such  a  penetration  of  dentin  has  been  reached  that  the  pulp  of 
the  tooth  becomes  hypersensitive  on  account  of  irritation  of 
its  tissue.  While  this  is  the  general  rule,  not  a  few  persons 
complain  of  more  or  less  pain  or  of  an  itching  sensation  almost 
as  soon  as  the  enamel  has  been  penetrated,  and  the  examination 
of  such  cavities  with  an  instrument  point  develops  the  fact  that 
they  are  sensitive  to  any  mechanical  interference.  Other  per- 
sons have  no  perception  of  anything  going  wrong  in  a  decaying 
tooth  until  they  notice  that  a  cavity  has  formed.  There  has  been 
no  pain  or  other  noticeable  sensation  because  of  caries  of  the 
dentin ;  this  is  the  general  rule.  Sensitiveness  in  the  early  stages 
of  caries,  without  some  mechanical  disturbance  to  arouse  it,  is 
the  exception,  though  it  is  by  no  means  rare. 

The  rule  is,  that  all  progressive  decays  in  teeth  with  living 
pulps  are  sensitive  to  any  form  of  mechanical  interference,  such 
as  probing  with  a  sharp  explorer,  or  to  the  use  of  cutting  instru- 


VITAL   PHENOMENA    IN    CARIES.  145 

ments.  This  sensitiveness  varies  greatly  in  different  persons 
and  in  different  carious  cavities  in  tlie  teetti  of  the  same  person. 
Therefore,  we  may  recognize  subnormal,  normal  and  hypernor- 
mal  sensitiveness.  Similar  grades  of  sensitiveness  will  be  found 
if  we  cut  into  the  dentin  of  perfectly  normal  teeth  free  from  all 
decay.  The  great  variety  of  grade  of  sensitiveness  in  normal 
healthy  dentin  has  seemed  to  me  very  remarkable.  Some  per- 
sons have  cut  into  so  many  teeth  that,  apparently,  were  not  sen- 
sitive at  all,  that  they  have  expressed  a  doubt  as  to  whether  a 
tooth  that  was  perfectly  normal  was  sensitive.  Even  in  these 
cases  of  failure  to  find  sensation  at  a  first  cutting,  sensation  is 
usually  aroused  and  it  may  soon  pass  the  normal  point  and 
become  hyi^ersensitiveness. 

Sensitiveness  to  cutting  instruments  is  not  materially  dif- 
ferent in  carious  teeth  from  normal  sensitiveness  of  dentin,  only 
that,  in  a  long  run  of  cases,  it  will  be  found  somewhat  greater 
for  equal  areas.  Those  who  have  had  some  experience  in  remov- 
ing enamel  from  living  teeth  in  the  preparation  of  abutments 
for  bridges,  have  found  that  a  high  degree  of  sensitiveness  has 
been  quickly  developed  in  a  large  proportion  of  cases.  This  is 
so  general  and  creates  so  much  difficulty  that  most  dentists  pre- 
fer to  destroy  and  remove  the  pulp  before  beginning  this  prep- 
aration. Sensitiveness  in  carious  teeth  is  not  greater;  it  seems 
to  be  subject  to  the  same  degree  of  increase  under  similar  treat- 
ment. Well  planned  and  firm  work  with  sharp  cutting  instru- 
ments arouses  the  least  sensitiveness;  dull  instruments  arouse 
much  more  sensitiveness  than  sharp  ones;  burs  arouse  much 
more  than  hand  instruments,  and  grinding  with  stones  more  than 
any  other  form  of  cutting. 

Sensitiveness  of  dentin  is  greatest  along  the  dento-enamel 
junction,  where  the  fibrils  are  much  branched,  and  diminishes 
perceptibly  in  the  deeper  parts.  For  this  reason,  practically 
the  whole  work  of  removing  the  enamel  cap,  as  in  preparing 
abutments  for  bridges,  is  cutting  in  the  area  of  most  acute  sen- 
sitiveness. For  the  same  reason,  broad,  shallow  areas  of  decay, 
such  as  are  often  found  in  labial  and  buccal  surfaces,  are  more 
sensitive  than  those  of  deeper  penetration  and  less  superficial 
breadth.  In  any  and  all  cavities,  the  more  sensitive  areas  are 
along  the  dento-enamel  junction  about  the  circumference.  In  a 
few  positions  the  form  of  the  finished  cavity  will  permit  of  cut- 
ting off  the  fibrils  supplying  such  a  part  deeper  in  the  dentin,  and 
save  considerable  pain  to  the  patient.  A  good  knowledge  of  the 
histological  structure  will  always  indicate  these  in  the  particular 


146  PATHOLOGY    OP    THE    HAED    TISSUES    OF    THE    TEETH. 

cases  in  which  they  occur.  It  is  difficult  to  understand  the  wide 
variations  of  sensitiveness  that  occur  in  different  cases,  some- 
times between  teeth  in  the  same  mouth,  but  more  commonly 
between  the  teeth  of  different  persons.  Occasionally,  we  may 
find  that  much  of  this  apparent  difference  between  persons  is  a 
difference  in  the  disposition,  or  ability  to  endure  pain.  Apart 
from  that,  however,  there  is  a  real  and  tangible  difference  among 
persons  in  the  sensitiveness  of  dentin.  The  teeth  of  some  per- 
sons are  extremely  sensitive,  no  matter  when  or  how  they  are 
cut,  while  the  teeth  of  others  are  not. 

The  rule  is  that  sensitiveness  of  the  dentin  to  cutting  instru- 
ments indicates  no  especial  danger  to  the  pulp  of  the  tooth,  no 
matter  how  extreme  it  may  seem  at  the  moment.  Generally,  it 
is  all  over  the  moment  the  cutting  is  done.  More  rarely  distinct 
pain  is  felt  for  some  time  after  the  cutting  is  finished.  Danger 
to  the  pulp  is  indicated,  however,  when  there  is  much  mutilation 
of  the  tooth,  as  by  cutting  away  the  enamel  with  a  considerable 
amount  of  dentin  over  wide  areas,  as  is  often  done  in  preparing 
teeth  for  abutments  of  bridges.  Distinct  hypersensitiveness  of 
the  pulp  tissue  itself  is  developed  and  also,  in  many  cases,  ther- 
mal sensitiveness  and  hyperemia,  which  may  seriously  endanger 
the  life  of  the  pulp. 

Seksation  in  dentin  is  derived  from  the  dentinal  fibrils. 
The  dentin  has  no  nerves.  Sensation  is  conveyed  by  the  fibrils. 
Whenever  those  of  any  part  are  cut  off,  the  dentin,  to  which  the 
severed  fibrils  are  distributed,  loses  sensation  at  once.  These 
fibrils  are  not  simply  glue-giving  fibers,  such  as  the  fibers  of 
ordinary  connective  tissue,  but  are  prolongations  from  the  odon- 
toblasts and  are  probal)ly  formed  of  the  same  material  as  the 
nuclei  of  these  cells.  I  have  removed  the  fibrils  from  the  den- 
tinal tu1)ules  for  a  considerable  length  and  stained  them  together 
with  the  odontoblasts  to  which  they  belonged,  and  found  them  to 
have  the  same  reaction  to  staining  agents  as  the  nuclei  of 
these  cells.  Eose  has  examined  this  point  with  great  care  and 
expresses  the  opinion  that  the  fibrils  are  not  glue-giving  mate- 
rial, as  are  ordinary  fibers,  but,  chemically,  are  closely  allied  to 
nuclein.  We  conclude,  therefore,  that  the  dentinal  fibril  is  a 
most  highly  endowed,  living,  functionating  tissue,  really  a  part 
of  the  odontoblast  —  a  prolongation  of  its  nuclein  and  a  func- 
tioning part  of  it.  Therefore,  when  we  have  touched  a  dentinal 
fibril,  we  have  touched  the  prolongation  of  an  odontoblast,  a 
living  part  of  the  cell  itself.  Th(>  odontol)laKts  are  in  physiologi- 
cal relation  to  nerve  endings,  as  has  been  demonstrated  by  many 


IF 


Fig.  159. 


Fio.    159.     A    diagram    illustrating   sensation   without   nerves   in    the   (initin.  e.    Knamol.  d. 

Dentin,  o.   Layor  of   odontoblasts.  I'.    Pulp  of  tooth   with   nerve  enriinirs   in   physiological   con- 

nection with  the  odontoblasts.  The  fibrils  of  the  tlentin  arc  )>rolongations  of  the  odontoblasts.  Any 
injury  to  tla-ui  is  an  injury  to  a  portion  of  the  odontoblasts  and  is  transmitted  by  the  nerves  to  the 
brain. 


VITAL   PHENOMENA    IN    CARIES.  147 

authorities,  lience  the  sensation  arising  from  an  injury  to  a 
dentinal  fibril  is  transmitted  to  the  brain  and  registered  as  pain. 
This  is  illustrated  in  the  diagram,  Figure  159.  An  injury  to  den- 
tinal fibrils  near  the  enamel,  e,  is  transmitted  through  the  thick- 
ness of  the  dentin,  d,  to  the  odontoblasts,  o,  without  nerves, 
because  the  cell  is  continuous  through  the  dentin.  The  impression 
is  then  transmitted  to  the  proper  conveyors  of  sensation  —  the 
nerves  in  the  pulp,  p,  and  by  them  to  the  brain. 

Sensation  is  a  fimction  of  living  cells  especially.  Nerves, 
while  they  may  have  sensation  of  themselves,  as  other  living 
tissue,  are,  functionally,  the  conveyors  of  sensation  from,  or 
impulses  to,  the  cellular  elements  of  the  body.  An  injury  to  a 
sensitive  nerve  trunk  is  usually  represented  in  the  sensorium  as 
coming  from  the  tissue  to  which  its  fibers  are  distributed.  Most 
persons  have  felt  the  shock  of  an  injury  to  the  ulnar  nerve  in 
the  little  finger  and  the  half  of  the  third  finger  next  to  it,  when 
they  have  struck  the  so-called  "crazy  bone"  near  the  elbow. 
This  is  because  the  nerve  injured  is  distributed  to  these  parts. 
Impulses  are  conveyed  outward  by  motor  nerves,  the  same  as 
the  impressions  of  pain  or  touch  are  conveyed  inward  by  sensory 
nerves.  A  muscular  fiber  is  often  very  long,  yet  there  is  gen- 
erally but  a  single  nerve  plate,  or  nerve  ending,  on  a  muscular 
fiber.  An  impulse  through  that  nerve  plate  may,  however,  set 
the  whole  length  of  the  muscular  fiber  into  contraction.  This  is 
the  analogue  of  the  transmission  of  the  sense  of  pain  through 
the  thickness  of  the  dentin  without  nerves. 

Besides  the  sensory  function,  the  dentinal  fibrils  have  also 
the  function  of  the  maintenance  of  the  integrity  and  qualities 
of  the  dentin.  It  goes  no  farther  than  this.  The  dentin  has  no 
reparative  functions.  The  fibrils,  though  highly  endowed  with 
sensation,  do  not  exhibit  any  function  of  repair.  But  that  there 
is  a  power  of  maintenance  of  the  qualities  of  the  dentin,  seems 
clear  from  clinical  evidence.  There  is  a  slow  but  distinct  dete- 
rioration in  the  qualities  of  the  dentin  in  pulpless  teeth,  which 
is  too  apparent  to  escape  the  clinical  observation  of  a  close 
observer  of  long  experience.  This  becomes  especially  apparent 
in  careful  laboratory  study.  The  enamel  is  much  easier  to  split 
off  from  the  dentin  in  teeth  that  have  long  been  pulpless.  The 
dentin  very  slowly  loses  strength  as  compared  with  neighboring 
living  teeth  from  the  same  or  other  mouths.  It  loses  much  of 
its  translucency,  loses  elasticity  and  becomes  more  brittle.  The 
younger  the  person  at  the  time  of  the  loss  of  the  pulp,  the  more 
rapidly  these  changes  occur.    This  occurs,  however,  much  less 


148  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

rapidly  in  teeth  that  have  been  so  treated  and  filled  that  no 
septic  matter,  saliva,  or  other  extraneous  decomposable  mate- 
rial has  reached  the  dentin,  than  in  those  in  which  the  dentin 
has  been  exposed  to  such  material.  This  much  has  been  clearly 
shown  by  my  own  examinations  of  the  physical  characters  of  the 
teeth.  In  cases  in  which  there  is  much  abrasion,  deposits  of  sec- 
ondary dentin  on  the  walls  of  the  pulp  chamber  often  obliterate, 
or  very  nearly  obliterate,  the  crown  portion  of  the  pulp.  The 
pulpal  ends  of  the  dentinal  tubules  are  closed,  cutting  off  the 
fibrils  of  the  crown  of  the  tooth  from  the  pulp.  Figures  160,  161. 
Where  this  is  complete,  as  often  occurs,  the  crown  of  the  tooth 
has  lost  its  vitality  and  undergoes  degeneration,  the  same  as  in 
teeth  that  have  lost  their  pulps.  Often  the  deterioration  will  be 
greater  in  these,  because,  apparently,  of  the  wide  area  of  dentin 
exposed  to  the  fluids  of  the  mouth.  A  perfect  enamel  covering, 
or,  in  case  of  a  cavity,  a  perfect  filling,  serves  to  limit  deteriora- 
tion. Filling  operations  in  such  teeth  should  always  be  con- 
ducted on  the  hypothesis  that  they  are,  or  will  become,  less  strong 
than  normal. 

How,  when  and  by  what  agency  are  the  dentinal  fibrils 
destroyed  in  dental  caries?  This  question  has  often  been  asked 
and  variously  answered,  but  I  Icnow  of  no  answer  based  upon 
evidence  that  seems  to  me  conclusive.  My  own  conclusion, 
derived  from  combined  clinical  and  laboratory  study,  has  been 
that  the  fibrils  are  practically  destroyed  between  the  line  of 
beginning  solution  of  calcium  salts  and  the  invasion  of  micro- 
organisms. In  other  words,  that  the  death  of  the  fibrils  is  not 
the  result  of  actual  contact  of  organisms,  but  always  a  little  in 
advance  of  them.  Also  that  many  of  the  fibi'ils  —  not  all  —  are 
destroyed  for  a  considerable  distance  in  advance  of  the  softening 
process,  or  even  to  the  pulp  itself,  and  that  this,  in  some  way, 
produces  the  flamelike  cloud  or  hyaline  area  of  Tomes,  streaking 
away  toward  the  pulp  from  a  carious  area.  This  whole  subject, 
however,  will  require  much  close  investigation  before  it  is  satis- 
factorily made  out. 

OBTUNDING   SENSITIVE   DENTIN. 

The  treatment  of  sensitive  dentin  for  the  purpose  of  reliev- 
ing or  limiting  the  pain  in  the  excavation  of  cavities,  has  been 
prominently  before  the  dental  profession  since  the  first  discovery 
of  anaesthesia,  and,  perhaps,  for  many  years  before  that  time. 
Personally,  I  have  watched  the  progress  of  this  effort  through 


Fio.   IfiO. 


Pio.   161. 


Figs.  160.  161.  Photographs  of  split  incisors  that  have  been  badly  abraided.  In  Figure  160  the 
outlines  of  what  was  the  pnip  chamber  are  sharply  apparent  in  the  incisal  portion,  but  the  whole  puln 
chamber  is  solidly  filled  with  a  calcific  deposit  which  has  obliterated  the  dentinal  tubnles.  cutting  off 
all  connection  of  the  dentinal  fibrils  with  the  pulp  of  the  tooth.  This  has  destroyed  the  vitality  of  the 
crown  of  the  tooth  and  obliterated  all  sensation  in  the  dentin.  In  Figure  161  there  is  very  nearly  the 
same  condition,  bi:t  in  the  light  line  in  the  central  portion  of  the  pulp  canal  there  was  a  shred  of 
living  pulp  tissue  that  may,  or  muy  not,  have  retained  connection  with  a  few  of  the  dentinal  fibrils 
of  the  crown  of  the  tooth. 


VITAL  PHENOMENA   IN   CARIES.  149 

many  years  of  what  has  been  fairly  close,  careful  observation  in 
clinical  practice,  and  always  with  an  earnest  desire  to  relieve 
patients  of  suffering  in  the  necessary  cutting  in  the  preparation 
of  cavities.  In  all  of  this  time,  and  up  to  the  present,  the  results 
have  been  so  poor,  or  so  uncertain,  that,  as  compared  with  skillful 
use  of  well-selected  cutting  instruments,  well  tempered  and 
always  sharp,  they  have  not  been  a  success.  I  do  not  mean  to 
say  by  this  that  pain  has  not  been  obtunded  and  made  less 
severe.  But,  through  fussing  with  such  obtuudants  as  have  been 
used,  the  dissipation  of  energy  by  the  operator,  the  repetition  of 
partial  failure  and  disappointment  to  the  patient,  the  increased 
time  employed,  and,  finally,  the  amount  of  injury  that  has  been 
done,  prompts  me  to  say  that  thus  far  the  operator  of  fair  skill 
will  do  his  patient  the  better  service  if  he  lets  obtundants  alone 
almost  entirely.  Thus  far,  the  man  who  bends  his  energies  to 
developing  the  most  thorough  systemization  of  the  use  of  cut- 
ting instruments  and  personal  skill  in  controlling  patients  suffer- 
ing pain,  will  dismiss  his  patient  at  the  end  of  an  operation  in 
better  condition  than  he  could  possibly  do  with  the  use  of  any 
local  or  general  obtundant  at  present  known. 

In  sajang  this,  I  am  not  unmindful  of  the  apparent  fact 
that  a  few  men  have  seemed,  personallj%  to  have  developed  a 
very  successful  use  of  some  particular  form  of  obtundant  and 
seem  to  have  done  much  good  by  its  use.  Many  will  remember 
the  great  craze  caused  by  the  introduction  of  cataphoresis  — 
the  electric  application  of  cocain  —  to  this  purpose  a  few  years 
ago.  It  was  shown  conclusively  that  pain  could  be  relieved,  or 
even  abolished  by  this  method,  and  thousands  of  men  were  send- 
ing orders  for  the  necessary  apparatus.  Soon  it  was  found  that 
in  the  hands  of  the  average  man,  or  even  of  those  much  above 
the  average,  great  harm  was  being  done  which  far  outweighed 
the  advantages.  Under  the  stimulus  of  demand,  manufacturers 
had  turned  out  an  immense  supply  of  the  apparatus  that  became 
so  much  junk,  practically,  over  night.  Yet,  I  know  a  few  men 
who  used  and  are  still  using  that  method  to  great  advantage  and 
without  the  evil  results  that  have  befallen  most  men  who  under- 
took its  use.  But  it  was  incapable  of  assimilation  by  the  mass 
of  even  the  better  professional  men. 

Other  obtundants  have  been  heralded,  with  less  ostentation, 
perhaps  have  been  tried  by  hundreds  of  dentists  and  then  faded 
out  of  the  memory  of  men.  Such  has  been  the  fate  of  every 
obtundant  for  sensitive  dentin,  except  a  few  now  on  trial,  that 
has  come  forward  during  seventy  or  more  years  of  dental  prae- 


150  PATHOLOGY   OF    THE    HAED    TISSUES    OF    THE    TEETH. 

tice.    But  the  relief  of  suffering  is  an  ever-present  duty  and  the 
search  for  this  very  desirable  thing  should  continue. 

THERMAL    SENSITIVENESS. 

The  consideration  of  thermal  sensitiveness  more  properly 
belongs  to  special  pathology  and  therapeutics,  but  it  is  so  closely 
interwoven  with  the  management  of  cases  in  tilling  teeth  that  it 
is  necessary  to  consider  it  here.  Thermal  sensitiveness  is  a 
peculiar  painful  sensation  in  the  teeth  caused  by  changes  of  tem- 
perature. This  may  be  illustrated  by  taking  ice-water  in  the 
mouth  and  letting  it  come  suddenly  in  full  contact  with  the  teeth. 
This  causes  sharp  pain,  lasting  only  a  moment,  the  character  of 
which  is  well  known  from  personal  experience  by  most  persons. 
This  is  peculiar  to  the  teeth,  no  other  tissue  in  the  body,  no  other 
organ,  showing  a  like  resistance  to  thermal  changes.  This  is 
normal.  Under  certain  conditions,  this  becomes  a  hypersensi- 
tiveness  to  thermal  changes ;  it  becomes  augmented  and  becomes 
a  pathological  condition.  The  actual  condition  in  this  case  is  a 
hy]3eremia  of  the  pulp.  There  is  an  injury  to  the  walls  of  the 
veins,  particularly,  and,  to  some  extent,  to  the  arterioles  of  the 
pulp,  by  which  they  become  very  much  dilated;  indeed,  each 
manifestation  of  pain  in  this  way  is  brought  about  by  a  dilation 
of  the  blood  vessels  of  the  pulp  and  forcing  of  an  extra  quantity 
of  blood  into  them.  When  the  walls  of  the  vessels  become  so 
injured  that  they  are  more  readily  expanded  than  normal,  this 
becomes  a  pathological  condition  and  every  slight  change  of 
temperature  produces  a  paroxysm  of  pain.  This  is  called  ther- 
mal sensitiveness.  It  is  entirely  separate  and  distinct  from  sen- 
sitiveness of  dentin.  We  may  have  sensitive  dentin  existing  and 
continuing  for  a  long  time  without  any  particular  thermal  sen- 
sitiveness, or  we  may  have  thermal  sensitiveness  without  abnor- 
mal sensitiveness  of  the  dentin,  or  we  may  have  the  two  existing 
together.    They  are  distinct  conditions. 

Thermal  sensitiveness  may  be  aroused  in  many  different 
ways.  It  is  sometimes  caused  in  the  incisor  teeth  by  the  heat 
of  a  cigar  in  smoking;  it  may  be  caused  suddenly  by  an  extraor- 
dinary exposure  to  cold,  as  ice-water;  it  may  be  caused  sud- 
denly by  exposure  to  hot  drinks,  and  the  dentist  may  develop  it 
suddenly  by  the  heat  of  a  disk  in  finishing  a  filling,  or  the  heat 
of  a  bur  in  excavating  in  any  tooth  that  has  a  living  pulp. 
Often  thermal  sensitiveness  is  aroused  during  the  progress  of 
decay,  especially  when  the  decay  has  reached  the  neighborhood 
of  the  pulp,  sometimes  when  the  decay  has  not  nearly  reached 


VITAL,   PHENOMENA   IN    CAIilES.  151 

the  pulp,  and  the  patient  will  have  paroxysms  of  pain  from  every 
exposure  to  thermal  changes.  Usually  these  pass  away  quickly. 
As  it  becomes  worse,  the  i^aroxysms  of  pain  will  continue  longer. 
This  continuation  of  the  paroxysms  of  pain  marks  the  severity 
of  the  case,  and,  finally,  if  it  continues  to  grow  worse,  the  patient 
will  have  pain  when  lying  down,  will  have  pain  at  night;  the 
diffei'ence  in  blood  pressure  between  the  horizontal  position  and 
the  upright  position  will  be  sufficient  to  determine  a  condition  of 
pain.  Cases  occur  occasionally  in  which  a  stream  of  water  three 
degrees  off  either  way  from  the  normal  temperature  of  the  body 
will  induce  excruciating  pain. 

In  the  management  of  cases,  it  is  of  the  utmost  importance 
that  we  recognize  what  may  occur,  and  exercise  due  caution  in 
the  use  of  disks,  whether  dry  or  lubricated,  stones  even  when 
wet,  or  in  running  burs  too  long  or  too  rapidly  in  excavating,  or 
any  of  these  things  that  are  calculated  to  produce  heat  which 
may  suddenly  precipitate  a  condition  of  hyperemia  of  the  pulp 
or  thermal  sensitiveness. 

There  is  only  one  thing  to  do  in  the  treatment,  and  that 
is  to  protect  the  ease  as  absolutely  as  possible  from  thermal 
changes  until  it  recovers.  This  may  be  done  in  various  ways. 
In  some  of  the  worst  cases,  caps  of  gutta-percha  may  be  put  over 
the  teeth  involved,  covering  them  in  completely,  particularly  for 
persons  who  must  be  out  in  the  cold  air.  Patients  may  protect 
the  teeth  from  thermal  changes;  they  may  avoid  cold  or  hot 
drinks;  they  may  avoid  cold  or  hot  foods;  they  may  avoid 
breathing  through  the  mouth  when  out  of  doors  in  cold  weather, 
and,  in  this  way,  protect  the  teeth.  This  is  very  much  the  best 
way  to  protect  them  from  thermal  changes.  Gutta-percha  caps 
over  the  teeth  will  be  very  annoying,  and  it  is  often  difficult  to 
induce  patients  to  wear  them.  A  thing  that  seems  so  simple  to 
do  often  becomes  very  annoying  because  of  failure.  But  the 
fact  is  that,  in  moments  of  freedom  from  pain,  patients  forget 
and  in  an  unguarded  moment  precipitate  another  paroxysm  of 
pain. 

Cases  of  very  severe  thermal  sensitiveness  will  generally 
get  well  promptly,  or  within  a  week  or  ten  days,  if  properly  pro- 
tected. Sometimes,  however,  it  may  require  more  time,  and 
whenever  we  find  thermal  sensitiveness  developed  to  any  extraor- 
dinary degree  so  as  to  be  very  annoying,  we  should  desist 
from  all  operations  upon  the  tooth  involved,  except  those  cal- 
culated to  mitigate  this  condition.  If  it  has  occurred  from  a 
cavity  of  decay,  it  is  best  to  remove  all  decayed  dentin  com- 


152  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE    TEETH. 

pletely  so  as  to  remove  the  irritants  in  the  decaying  mass.  When 
the  cavity  is  prepared,  it  should  not  receive  a  metallic  filling, 
but  a  temporary  filling  of  gutta-percha,  which  should  be  a  tight 
filling.  The  walls  should  be  dried  first,  as  dry  as  absorbent  cot- 
ton will  make  them ;  they  should  then  be  moistened  slightly  with 
eucalyptol,  so  that  the  gutta-percha  will  adhere  and  make  the 
filling  tight.  This  is  the  best  treatment,  for  gutta-percha  is  the 
best  nonconductor  we  have  with  which  to  make  these  temporary 
fillings.  A  gold  filling  at  such  a  time  would  be  contra-indicated, 
because  it  so  readily  conducts  thermal  changes.  Time  should 
be  allowed  for  the  sensitiveness  to  disappear  before  making  anj^ 
other  operations  upon  the  tooth,  and,  if  the  condition  is  severe, 
all  operations  in  the  mouth  should  be  omitted  until  that  tooth 
shall  have  recovered ;  or,  at  least,  any  operations  that  are  not 
absolutely  necessary  at  the  time. 

This  condition  often  ends  in  death  of  the  pulp  from  stran- 
gulation, which  leads  to  infarction.  To-day  the  tooth  may  be 
extremely  sensitive  to  thermal  changes;  to-morrow  the  pulp 
may  be  dead  and  this  sensitiveness  may  have  disappeared  com- 
pletely. The  sudden  disappearance  of  this  thermal  sensitiveness 
marks  certainly  the  death  of  the  pulp,  and  when  the  pulp  of  a 
tooth  has  died  under  these  conditions,  it  is  of  extra  importance 
that  it  be  removed  as  quickly  as  possible.  There  is  more  blood 
than  normal  in  the  pulp  at  the  time  of  its  death  and  the  blood 
globules  are  very  liable  to  be  broken  up  and  the  hemoglobin  set 
free  in  solution.  This  may  penetrate  the  dentinal  tubules  in 
every  direction,  a  red  color  appearing  through  the  enamel.  Such 
a  tooth  is  likely  to  become  very  dark  in  time,  and  it  is  especially 
difficult  to  bleach  it.  Early  removal  is  also  important  for  the 
reason  that  pericementitis,  and  possibly  alveolar  abscess,  may 
soon  develop  after  the  pulp  has  died.  This  condition  of  thermal 
sensitiveness  will  come  up  continually  in  the  cases  in  practice, 
and  require  treatment  along  with  the  other  items  in  the  manage- 
ment of  conditions  in  filling  operations. 


MANAGEMENT    OP    PATIENTS.  153 


MANAGEMENT  OF  PATIENTS. 

In  dentistry  there  is  nothing  more  important  than  the  devel- 
opment of  skill  in  the  management  of  people  in  their  sufferings, 
or  in  so  managing  patients  as  to  gain  the  opportunity  to  do  that 
which  is  necessary  and  best  for  them  and  to  do  operations  in  the 
best  way.  A  student  came  to  me  and  complained  that  he  could 
not  place  the  rubber  dam  for  a  lady  in  his  chair,  stating  that 
she  could  not  bear  to  have  it  in  her  mouth.  I  went  to  the  patient, 
spoke  a  few  encouraging  words,  and  started  to  place  the  rubber 
dam.  There  was  some  spasmodic  retching,  which  I  assured  her 
would  pass  away  in  a  moment.  Then  I  linished  placing  the  dam 
without  apparent  discomfort  to  her.  There  was  nothing  wrong 
with  the  patient,  except  that  she  had  come  with  a  prejudice 
toward  the  rubber  dam  that  needed  to  be  recognized  and  over- 
come. Patients  will  have  their  little  prejudices  and  notions  that 
interfere  with  their  comfort  and  with  the  performance  of  neces- 
sary operations  for  their  benefit.  The  dentist  should  learn  to 
appreciate  these  quickly  and  develop  the  tact  to  smooth  them 
away.  The  management  of  these  is  not  well  within  our  power 
to  teach  with  any  set  of  maxims  or  rules.  Men  of  widely  dif- 
ferent temperament  and  trend  of  thought  seem  to  manage  people 
equally  well.  But  in  all  there  is  a  feeling  of  profound  respect 
for  people  in  suffering  and  an  earnest  desire  to  aid  them,  which 
serves  as  the  basis  of  thought  and  action.  With  such  a  basis, 
and  a  careful  study  of  mental  states  and  qualities  of  mind,  of 
conditions  and  impulses  that  move  men,  or  influence  people's 
thought,  one  should  succeed.  It  sometimes  seems  to  be  more 
important  that  the  dentist  should  begin  his  professional  work 
with  a  well  grounded  notion  of  the  humanities  and  of  the  psychic 
nature  of  man  than  the  devotees  of  any  other  profession.  The 
nature  of  his  calling  keeps  him  indoors  —  secludes  him  from  the 
more  general  social  and  semi-professional  mixture  with  people; 
he  is  confined  with  one  patient  at  a  time  day  after  day.  The 
physician  is  going  hither  and  yon,  mingling  with  people  socially, 
semi-prof essionally  or  professionally  continuously;  he  has  the 
opportunity  of  studying  the  psychic  conditions  in  those  whom 
he  meets  tenfold  more  than  the  dentist.  Yet  the  dentist  needs 
such  information  of  people,  and  the  impulses  that  move  them  to 
action  in  this  direction  or  that,  that  he  will  be  able  to  read  in 
their  actions  the  manner  of  approach  that  will  influence  the 


154  PATHOLOGY    OF    THE    HABD    TISSUES    OF    THE   TEETH. 

particular  person  best,  or  place  liim  or  her  in  a  state  of 
mind  that  will  give  the  opportunity  to  do  dental  operations  to 
the  best  advantage  and  greatest  good  to  the  patient.  This 
requires  a  close  sympathy  of  mind  with  mind,  a  development  of 
confidence  on  the  part  of  both  operator  and  patient,  a  matter 
that  every  dentist  should  cultivate  with  great  care. 

The  dentist  has  a  duty  also  as  a  teacher  while  doing  his 
duty  as  an  operator.  His  professional  life  should  be  an  exhibit 
of  the  helpfulness  that  earnest  dentistry  can  be  to  his  commun- 
ity. This  gives  him  power  for  good.  Aside  from  this,  he  should 
in  his  daily  office  work  be  continually  but  judiciously  giving 
information  regarding  dentistry  that  will  be  helpful  in  devel- 
oping the  ability  of  people  to  make  the  best  use  of  dentistry. 
To-day  only  about  fourteen  per  cent  of  the  people  of  America 
employ  dentists  or  make  any  intelligent  use  of  dentistry.  Still, 
no  other  country  has  done  as  well.  We  can  and  will  do  better, 
and  every  dentist  has  a  duty  in  furthering  the  information  of 
the  people  to  this  end.  This  he  can  do  best  in  his  professional 
intercourse  with  patients  in  his  own  office  by  giving  judicious 
and  careful  advice  that  will  be  helpful  on  any  points  that  may 
come  up.  That  which  proves  helpful  to  one  person  will  gradually 
be  disseminated  to  others,  and,  in  time,  the  whole  community 
will  be  benefited  and  will  make  a  wiser  and  better  use  of  den- 
tistry. Much  more  good  is  done  through  these  bits  of  informa- 
tion thus  given  in  a  careful  manner  at  proper  times  than  can  be 
imparted  in  any  amount  of  printed  matter,  however  wisely  writ- 
ten, intended  to  give  the  people  information  as  to  the  care  of 
their  teeth. 

Cleanliness. 

Cleaning  which  patients  should  do  for  themselves.  One 
of  the  imi^ortant  features  of  the  management  of  a  practice  is 
the  management  of  the  artificial  cleaning  of  patients'  mouths, 
or  instruction  of  patients  in  the  use  of  the  brush,  the  toothpick, 
silk  floss,  rubber  bands,  etc.,  and  the  recognition  of  conditions 
under  which  these  should  be  used.  Persons  will  be  found  who 
have  no  use  for  any  of  these  things,  persons  whose  mouths  will 
be  clean  without  them.  Examine  them  before  breakfast,  after 
breakfast,  or  any  other  time  of  day,  and  the  mouth  will  be  found 
clean,  there  will  be  no  lodgments  of  food,  there  will  be  no  debris 
about  the  teeth.  They  have  no  use  for  tooth  brushes,  they  have 
no  use  for  toothpicks  or  any  of  these  affairs  for  artificial  clean- 
ing.    Such  mouths  are  practically  perfect;    the  health  of  the 


MANAGEMENT    OF    PATIENTS.  155 

person  is  generally  good,  there  is  immunity  from  decay  and  they 
go  along,  possibly  through  life,  without  any  need  for  artificial 
cleaning.  There  are  no  deposits  from  the  saliva  of  these  persons, 
their  saliva  is  thin  and  watery  and  seems  to  dissolve  and  remove 
the  last  trace  of  debris.  But  such  perfect  conditions  are  the 
exception  to  the  rule. 

The  tooth  brush.  Most  persons  need  to  use  the  tooth 
brush,  and  it  becomes  the  duty  of  the  dentist  to  prescribe  the 
manner  of  its  use;  not  only  to  prescribe  the  manner  of  use, 
but  to  teach  his  patients  the  correct  use  of  the  brush.  Nearly 
every  person  who  uses  the  brush  will  fall  into  certain  fixed 
habits.  Some  will  take  the  brush  and  make  a  few  strokes  in  this 
direction  or  that,  and  are  done.  They  have  brushed  their  teeth, 
and  they  will  tell  you  very  conscientiously  that  they  have  brushed 
them  carefully.  Others  will  use  the  brush  vigorously.  They 
form  the  habil  of  going  through  certain  motions.  An  examina- 
tion will  show  the  cleaning  to  be  very  imperfect  in  that  certain 
parts  are  missed  and  not  cleaned  at  all.  Make  it  a  rule  to  say  to 
little  patients,  "The  next  time  you  come,  bring  your  brush  with 
you ;  I  want  to  see  how  you  brush  your  teeth. ' '  They  will  gen- 
erally do  it  very  carefully,  better  than  they  do  it  at  home;  or 
some  will  and  some  will  not.  Impress  in  some  way  the  lesson 
that  it  is  necessary  for  them  to  do  this  thing  carefully,  and  then 
prescribe  the  method  of  doing  it.  One  may  brush  the  buccal 
surfaces  of  the  teeth  with  a  back-and-forward  motion,  but  this 
will  not  brush  the  embrasures  well;  the  bristles  of  the  brush 
will  not  get  in  toward  the  proximal  surfaces  of  the  teeth.  Teach 
patients  to  use  the  up-and-down  motion  along  the  length  of  the 
teeth ;  the  bristles  of  the  brush  will  go  into  the  embrasures  and 
clean  the  surfaces  close  to  the  contact  points  when  used  in  this 
way.  This  may  be  done  all  over  the  mouth.  It  is  just  as  easy  a 
motion  as  the  other  when  once  learned.  The  manner  of  brushing 
will  depend  a  good  deal  upon  the  tendencies  in  the  case.  Children 
and  young  people  particularly,  should  brush  their  teeth  with  this 
up-and-down  motion,  for  the  tendency  in  them  is  usually  for  the 
formation  of  proximal  cavities.  As  they  come  to  adult  age, 
there  is  more  necessity  for  brushing  the  buccal  surfaces;  they 
are  more  liable  to  be  developing  gingival  third  cavities.  If 
patients  are  found  with  a  tendency  to  the  development  of  gingi- 
val third  cavities,  the  back-and-forth  motion  becomes  the  impor- 
tant method  of  brushing,  because  it  cleans  the  portions  of  the  sur- 
faces of  the  teeth  that  are  then  most  liable  to  decay.  Wherever 
patients  show  a  tendency  to  buccal  decays,  say  to  them,  "By 


156  PATHOLOGY    OF    THE    HARD    TISSUES   OF   THE    TEETH. 

care  in  brushing  you  may  avoid  other  cavities  in  similar  positions, 
for  this  is  a  part  of  the  tooth  that  you  can  clean,  and,  if  you  do 
it  well,  you  will  stop  all  of  the  tendency  to  decay  in  these  sur- 
faces." These  surfaces  are  in  positions  that  can  be  reached 
and  can  be  cleaned  perfectly  with  the  brush  and  water  without 
other  aids.  Caries  will  not  begin  on  well-cleaned  surfaces  of 
the  teeth.  If  there  is  any  one  fact  regarding  decay  of  the  teeth 
that  is  well  fixed  by  careful  clinical  observation,  it  is  this  one. 
Of  all  the  surfaces  of  the  teeth,  the  buccal  and  labial  sur- 
faces are  cleaned  with  the  brush  the  easiest  and  most  per- 
fectly. To  do  this  properly,  however,  the  brush  must  be  used 
so  that  the  teeth  will  be  well  brushed  fully  to  the  free  margins 
of  the  gums.  Proximal  surfaces  or  fissures  can  not  be  perfectly 
cleaned  with  a  brush.  The  cleaning  of  the  lingual  surfaces  is 
mostly  for  the  purpose  of  preventing  disease  of  the  gums.  One 
can  run  around  all  of  these  surfaces  with  a  motion  very  nearly 
lengthwise  the  arch  with  an  ordinary  tooth  brush.  Only  the 
lower  second  and  third  molars  will  need  a  diagonal  motion. 
There  are  very  few  persons  who  need  other  than  the  ordinary 
straight  tooth  brush.  A  cheap  tooth  brush  is  generally  the  best 
tooth  brush,  because  it  is  small,  there  are  not  so  many  bristles  in 
it,  and  they  will  get  in  between  the  teeth  better. 

The  frequency  of  using  the  brush  is  an  important  item. 
This  should  be  regulated  somewhat  by  the  needs  of  the  particu- 
lar person.  Some  persons  do  not  need  to  use  a  brush.  On 
accoimt  of  our  artificial  manner  of  preparing  food,  we  do  not 
make  that  use  of  the  teeth  that  Nature  seems  to  have  intended. 
If  patients  form  the  habit  of  using  the  brush,  they  will,  once  the 
habit  becomes  fixed,  prefer  to  do  it.  It  is  necessary,  however, 
for  the  dentist  to  watch  them  carefully  until  this  becomes  a  fixed 
habit.  In  persons  where  the  susceptibility  to  caries  is  not  great, 
moderate  use  of  the  brush  is  sufficient;  in  fact,  many  persons, 
if  they  use  the  brush  once  a  day,  will  do  well  and  will  perhaps 
have  no  necessity  for  using  it  more  frequently,  but  the  habit 
of  using  the  brush  after  each  meal  is  the  best.  This  is  sufficient 
to  keep  oif  calculus  and  keep  the  gums  in  condition ;  but  where 
we  use  the  brush  as  a  prophylactic  against  cai'ies  of  the  teeth, 
and  especially  where  the  tendency  to  caries  is  very  considerable, 
the  brush  ought  to  be  used  as  often  as  four  times  per  day  —  after 
each  meal  and  at  night  before  retiring.  This  frequency  is  neces- 
sary to  prevent  the  formation  of  colonies  of  microorganisms, 
or  microbic  plaques  in  positions  reached  by  the  brush.  If  it  does 
not  entirely  prevent  proximal  decay,  it  will  materially  lessen 


MANAGEMENT    OF    PATIENTS.  157 

the  bucco-lingual  breadth  of  the  decay,  and  in  filling  these  cavities 
for  those  who  have  this  habit  well  fixed,  the  necessity  for  breadth 
of  cutting  in  extension  for  prevention  will  not  be  so  great, 
because  cleanliness  extends  deeper  into  the  embrasures. 

We  sometimes  hear  of  the  brush  doing  injury  to  the  teeth. 
It  does  not  seem  possible  that  the  brush,  used  with  water  only, 
will  do  injury  to  the  hard  tissues  of  the  teeth.  In  some  cases 
it  has  appeared  as  though  the  brush  might  be  responsible  for 
injury  to  the  teeth  near  the  gum  margin,  but  other  cases  where 
the  brush  had  not  been  used  at  all  are  so  nearly  like  these  as 
to  show  that  the  injury  had  not  been  done  by  severe  brushing. 
Sometimes  it  would  seem  that  the  gum  had  been  torn,  lacerated 
and  caused  to  recede,  particularly  from  the  upper  cuspid  teeth 
on  the  labial  surface.  It  would  seem  that  we  might  easily  injure 
the  gums  in  this  position  and  cause  a  recession  by  the  too  vigor- 
ous use  of  a  stiff  brush;  and  yet,  again,  many  cases  of  appar- 
ently the  same  kind  of  recession  appear  where  a  brush  has  not 
been  used.  This  brings  us  to  doubt  whether  even  this  has  been 
caused  by  the  too  vigorous  use  of  the  brush.  In  a  number  of 
these  cases  it  was  found  that  the  patient  failed  to  brush  these 
points.  Yet  the  dentist  should  have  a  care  about  the  vigorous 
use  of  a  very  stiff  brush  if  he  saw  a  tendency  to  this  kind  of 
recession ;  in  fact,  it  is  not  well  to  use  a  very  stiff  tooth  brush 
in  any  case;  a  brush  with  comparatively  few  bristles,  the 
bristles  being  sufficiently  strong,  but  not  so  many  of  them  as  to 
make  it  very  stiff  and  harsh,  is  better.  Injury  by  the  vigorous 
use  of  such  a  tooth  brush  is  not  to  be  feared.  A  few  persons 
will  be  met  with  who  state  that  they  use  the  brush  several  times 
a  day  for  ten  or  even  fifteen  minutes.  This  is  too  much  and 
should  be  moderated.  Any  one  ought  to  do  sufficient  brushing 
in  from  two  to  five  minutes. 

MoxjTH  WASHES,  TOOTH  POWDERS,  ETC.  What  mouth  wash 
should  be  used  with  the  brush?  What  the  mouth  wash  is, 
is  not  important.  Plain  water  answers  a  good  purpose  and 
is  sufficient,  but  it  is  often  a  valuable  point  to  prescribe  some 
particular  mouth  wash  for  this  or  that  person.  If  it  does 
no  other  good,  it  seems  to  have  an  influence  in  inducing  patients 
to  use  the  brush.  Many  persons  have  more  confidence  in  the 
use  of  some  wash  of  this  kind  than  they  have  in  the  mechani- 
cal cleaning,  and  wherever  a  mouth  wash  will  do  good  in 
this  way  it  should  be  prescribed.  But  never  prescribe  any 
tooth  powder,  or  tooth  paste,  or  other  mixture  that  contains 
any  kind  of  grit.    Dr.  W.  D.  Miller's  report  of  his  experimental 


158  PATHOLOGY    OF    THE    HARD    TISSUES   OF   THE   TEETH. 

work  on  erosion  shows  clearly  that  these  may  do  harm,  and  also 
that  many  of  the  tooth  powders  offered  on  the  market  contain 
much  grit.  It  is  best  not  to  i^rescribe  any  kind  of  tooth  powder. 
We  can  not  render  the  mouth  aseptic  by  the  use  of  any  of  the 
antiseptic  mouth  washes.  This  has  been  tried  very  thoroughly 
by  Dr.  Miller.  He  reports  that  he  was  unable  to  render  his  own 
mouth  aseptic.  He  could  remove  most  of  the  microorganisms 
for  the  time  being,  but  in  a  few  hours  they  would  be  as  plentiful 
in  the  mouth  as  before.  My  own  experiments  have  given  similar 
results.  The  most  we  can  do  is  to  eliminate  those  not  habitual 
in  the  mouth.  Most  of  the  microorganisms  that  are  not  habitual 
in  the  mouth,  i.  e.,  whose  natural  habitat  is  not  in  the  mouth, 
can  be  effectually  removed  by  the  use  of  antiseptic  mouth  washes, 
coupled  with  vigorous  mechanical  cleaning.  The  same  can  be 
done  just  as  well,  probably,  by  the  mechanical  cleaning  alone. 
I  have  found  that  the  pus  microorganisms,  the  staphylococci, 
except  the  one  white  staphylococcus  which  is  habitual  in  the 
mouth,  could  be  very  effectually  removed  by  the  use  of  the  brush. 
I  have  tried  this  with  nurses  in  the  hospitals  who  were  dressing 
suppurating  wounds.  Nurses  who  were  dressing  suppurating 
wounds  generally  had  pus  microorganisms  in  their  saliva  before 
the  closer  drill  of  recent  years  taught  them  better  plans  of 
aseptic  and  antiseptic  work.  These  can  be  very  effectually 
removed  within  a  few  days  so  that  we  will  be  unable  to  find  pus 
microoorganisms  in  the  mouths  of  these  persons  in  plant  after 
plant.  If  they  are  taught  especial  care  as  to  reinfection,  their 
mouths  can  be  kept  fairly  free  from  pus  microorganisms  or 
other  pathogenic  microorganisms,  except  those  whose  natural 
habitat  is  the  mouth.  These  we  are  utterly  unable  to  effectively 
remove.  Of  course,  the  harmless  saprophites  floating  in  the 
atmosphere  are  continually  being  caught  in  the  saliva,  and  it  is 
soon  reinfected  with  them.    These  are  of  no  consequence. 

The  toothpick,  ligature,  tape  and  rubber  bands.  As  the 
proximal  surfaces  of  the  teeth  can  not  be  cleaned  with  the 
brush,  it  is  necessary  to  use  other  means,  and  the  ordinary 
rubber  bands  and  the  silk  floss  are  best.  One  may  carry  a  ball 
or  a  disk  of  silk  floss  in  his  pocket,  or  have  one  on  his  dresser, 
or  may  carry  a  few  small  rubber  bands.  They  are  cheap  and 
may  be  used  and  thrown  away.  The  rubber  band  is  perhaps 
better  and  easier  handled  tlian  the  silk  floss  for  cleaning  the 
proximal  surfaces.  It  is  a  very  simple  matter  to  use  it;  pass 
the  rubber  band  into  the  interproximal  space,  bring  it  against 
the  distal  surface  of  one  tootb,  well  under  the  gingivae,  rub  that 


MANAGEMENT    OF    PATIENTS.  159 

back  and  forth,  bringing  it  out  at  the  occlusal;  then  against  the 
mesial  surface  of  the  next  tooth,  and  so  on  around  the  arch. 
Generally,  it  is  a  pretty  difficult  thing  to  get  patients  to  clean 
all  of  the  proximal  surfaces.  If  it  is  a  full  denture,  there  are 
sixty-four  surfaces  to  clean;  it  requires  sixty-four  distinct 
motions  to  go  around  the  arch  and  clean  all  of  these  surfaces. 
It  is  a  simple  matter  to  clean  one  or  two  or  three,  but  to  get 
the  patient  to  clean  all  of  them  and  do  it  regularly  is  quite 
another  matter.  It  takes  a  little  time,  not  very  much;  but  to 
form  the  habit  in  such  a  way  as  to  clean  every  proximal  surface 
is  difficult,  and  very  few  persons  accomplish  it  completely  for 
any  considerable  length  of  time. 

Perhaps  the  use  of  toothpicks  is  the  most  common  method 
of  cleaning  proximal  surfaces,  but  the  toothpick,  as  it  is  habit- 
ually used,  removes  only  lodgments  of  food.  With  the  tooth- 
pick, however,  the  proximal  surfaces  may  be  pretty  thoroughly 
cleaned;  microbic  plaques  that  have  been  formed  upon  these 
surfaces  can  be  removed,  but  generally  it  is  very  imperfectly 
done.  For  this  purpose  the  quill  toothpick  is  much  better  than 
the  ordinary  wooden  toothpick.  Nowadays  machinery  has  been 
made  for  making  the  wooden  toothpicks  and  large  factories  are 
established  for  the  purpose,  and  they  have  become  so  very  cheap 
that  every  one  may  use  them.  But  the  wooden  toothpicks  that 
come  to  us  are  not  always  perfectly  smooth.  There  is  more  or 
less  slivering  of  the  wood  in  many  of  them,  and  we  are  liable,  in 
using  these  toothpicks,  to  leave  little  slivers  of  wood  in  the  gum 
tissue  that  do  injury.  A  good  many  cases  of  injury  are  caused 
by  forcing  spiculae  of  wood  into  the  peridental  membrane 
between  the  tooth  and  its  alveolar  wall,  causing  soreness  and 
suppuration.  However,  some  wooden  toothpicks  are  made  very 
smooth  and  very  nice ;  but,  upon  the  whole,  the  quill  toothpicks 
are  very  much  the  better  to  use ;  they  will  get  into  places  where 
the  wooden  toothpicks  will  not  reach  and  will  clean  the  surfaces 
better. 

The  difference  in  persons  as  to  the  need  of  toothpicks  is 
very  great  indeed.  Most  young  people  have  very  little  use  for 
the  toothpick,  if  their  teeth  are  well  formed,  if  the  proximal 
contacts  are  good.  The  rubber  band  is  much  better.  "WTiere- 
ever  lodgments  occur,  the  person  should  be  instructed  to  use 
the  toothpick  and  to  use  it  regularly  after  eacb  meal.  Persons 
who  habitually  have  lodgments  between  their  teeth  are  very 
liable  to  neglect  them;  the  lodgment  from  one  meal  remains 
until  the  next  meal,  and  that  original  lodgment  is  forced  farther 


160  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE   TEETH. 

on  to  the  gum  tissue  and  a  new  lodgment  occurs,  and  this  con- 
tinues meal  after  meal,  day  after  day,  until  the  gum  tissue  is 
pushed  aside,  and  a  great  pocket  is  formed  between  the  teeth. 
If  this  food  lies  continually  between  the  teeth,  fermentation  will 
go  on,  giving  rise,  perhaps  to  caries ;  or  putrefactive  decompo- 
sition may  occur  with  disease  of  the  peridental  membrane.  Many 
eases  of  disease  of  the  gums  are  begun  in  that  way,  and  the 
dentist  should  guard  this  point  very  carefully. 


Fio.  1G2.     The  grnathodynamomcter,  about  two-thirds  natural  size.     Face  view.  c,  c.  The  nibber 

pads  bitten  upon  in  determining  the  pressure  of  the  teeth.         d.  Scale  of  pounds.  E.  Needle  which 

marks  the  povinds.     In   use  this  needle  rcmaina  stationary   at   the  highest  point  reached   until   it   is 
moved  by  the  fingers. 


FlQ.  163. 


Fio,  163.     The  back  view  of  the  gnathodyimmonieter.  a.  The  rigid  bar. 

,  c.  The  rubber  pads  bitten  upon  in  determining  the  pressure  of  the  teeth. 


u.   Tlie  spring  bar. 


So;        S:£i^=i-5'' 


tD 


•     BJ    C 


£«f,te^-^^  S      E.2 
S  S  2  o--" 


;  &* 


C^X 


a;  C  o 

-2  £:5 


-^^^      -  c  =  g 
^*j  —  a>  o  S      ,5   I 


!  a;  q 


■r",  t-  -^  .--  i.~  ^-   Q.  O   ^"^  "T,  ^ 


-     t:     p  S  o  3 


•3  1=-- 


cJ2  ■- 


■=  "  S  = 
c^g  g  S  act:  MO      B 

1 .2  o  "•  "^  -e:  ..  5  •=  ^  - 
e  o  <u ' 

s  i- " "  ~  ° "  £ « ■"  •  = 

i^x.'^^SS^®'-'??      E 
E         E,.<'-5S:  =  n 

h-rt      ..:;_-      ocrti 


•  i:  S  &c. 


-■5  : 


!.■= 


*j  —  ^  ftJT!^  a;-"  ?  =  _« 

..M.2a;C^coB.S  —  c_ 
=•"   I    «i.„C       a  i-°c 

"l-SiS^iTjE-Sl 

COr-O"     -OCO'^-'-S 

ccccmoo-nCoaa 


0*0 


2§ 


THE   FOBCE    USED   IN    MASTICATION.  161 


THE  FORCE  USED  IN  MASTICATION  IN  RELATION  TO 

THE  STRENGTH  AND  HEALTH  OF  THE 

PERIDENTAL  MEMBRANE. 

The  Force  Used  in  Chewing  Foods, 
illustrations:  figures  162165. 

Until  recently  there  was  no  accurate  knowledge  of  the  force 
used  in  mastication.  Inquiry  was  begun  in  1893,  and  in  my 
articles  on  "Physical  Characters  of  the  Human  Teeth,"  etc. 
(Dental  Cosmos,  1895),  a  pretty  full  exhibit  of  the  subject  was 
given.  Since  that  time,  the  subject  has  frequently  been  under 
investigation.  The  results  then  given  underwent  severe  question- 
ing, but  have  not  been  materially  changed  by  further  examination. 
There  have,  however,  been  published  some  results  obtained  with 
rudely  constructed  instruments  that  have  been  different,  evi- 
dently through  inaccuracy  of  observation,  and  others  apparently 
different  through  misconceptions  of  the  nature  or  of  the  condi- 
tion of  material  used. 

The  force  of  the  bite,  or  the  poimds  force  with  which  the 
jaws  may  be  closed  upon  any  object,  varies  greatly  among  differ- 
ent persons,  and  is  dependent  in  larger  degree  upon  the  condi- 
tion of  the  peridental  membranes  and  upon  personal  habits  in 
the  use  of  the  teeth  in  mastication  than  upon  muscular  power. 
It  has  been  my  habit  to  make  a  trial  of  the  force  of  the  bite 
every  year  among  the  students  of  my  classes  and  record  the 
results.  In  these  tests  a  familiarity  with  the  instrument  was 
brought  out  and  rivalry  was  pretty  sure  to  occur  among  those 
of  the  highest  strength  which  served  to  develop  the  full  power 
of  the  occlusion.  In  a  tabulation  of  results  in  one  thousand 
persons,  the  average  force  exerted  was  171  pounds  on  the  molar 
teeth,  and  considerably  less  on  bicuspids  and  incisors.  In  this, 
there  was  no  selection  of  persons,  further  than  a  careful  exclu- 
sion from  the  trials  of  persons  whose  teeth  were  so  badly  weak- 
ened by  caries  as  to  cause  danger  of  injury  by  breakage.  In 
spite  of  this  prohibition,  there  were  a  few  accidents  to  cusps 
of  teeth  that  had  very  large  fillings.  The  variation  was  from 
25  poimds  to  275  pounds.  Two  hundred  and  seventy-five  pounds 
is  the  full  register  of  the  instrument  used  and  among  the  trials 
there  were  seventeen  persons  who  made  this  full  register.  A 


162  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

number  of  these  could  have  registered  a  greater  number  of 
pounds.  The  instrument  used  is  called  the  gnathodynamometer. 
Figures  162,  163.  A  variation  from  accuracy  of  results  occurs 
from  biting  very  close  to  the  end  of  the  rubber  pads,  or  from 
catching  too  far  from  the  ends,  which  may  altogether  produce 
an  error  of  about  ten  per  cent.  With  this  exception,  the  instru- 
ment is  as  accurate  as  ordinary  spring  scales.  In  these  trials, 
the  instrument  generally  rests  on  two  teeth  in  one  jaw  and  but 
one  in  the  other.  It  is  only  occasionally  that  it  can  be  so  placed 
as  to  rest  fairly  on  two  teeth  in  each  jaw. 

The  force  of  the  bite  of  an  individual  is  modified  very  mate- 
rially (1)  by  the  use  habitually  made  of  the  teeth,  (2)  by  the  loss 
of  the  pulp,  (3)  by  disease  of  the  peridental  membranes.  Nearly 
every  one  who  makes  trial  of  his  bite  on  the  gnathodynamometer 
stops  because  of  pain  in  the  peridental  membranes  rather  than 
from  having  reached  the  full  limit  of  muscular  effort.  There- 
fore, modification  of  the  condition  of  these  membranes  is  promi- 
nently brought  oi;t.  Full  and  free  use  of  the  teeth  in  mastication, 
and  especially  the  disposition  to  use  them  freely  on  hard  foods, 
contributes  to  strength.  Any  considerable  limitation  of  the  use 
of  the  teeth,  for  even  a  few  days,  shows  in  tenderness  of  the 
peridental  membranes,  and,  in  cases  where  the  person  has  fallen 
into  the  habit  of  swallowing  food  practically  without  mastica- 
tion, the  power  of  the  bite  will  be  found  as  low  as  fifty  pounds, 
or  even  lower.  Any  considerable  pressure  causes  pain.  Very 
marked  cases  of  this  loss  of  power  occasionally  occur  where 
persons  have  fallen  into  the  habit  of  disuse  of  the  teeth  because 
of  exposure  of  the  pulp  in  one  or  two  teeth,  which  causes  pain 
that  prevents  them  from  chewing  their  food.  In  such  cases, 
bolting  of  food  is  liable  to  become  habitual.  This  condition  is 
readily  recovered  from  by  careful  training. 

In  disease  affecting  the  peridental  membranes,  the  power 
of  the  occlusion  is  rapidly  reduced ;  that  is,  the  muscles  of  masti- 
cation are  held  from  exerting  their  full  power  by  pain  warning 
them  to  go  no  farther.  A  tooth  from  which  the  pulp  has  been 
removed  seems  never  again  to  completely  recover.  Even  though 
the  person  has  not  recognized  the  difference  in  the  ordinary 
use  of  the  teeth,  it  shows  in  these  trials.  The  difference  is 
generally  considerable,  but  there  are  wide  variations. 

Therefore,  the  limitations  of  the  force  of  the  occlusion  as 
shown  by  the  gnathodynamometer  is  a  register  of  the  power 
of  resistance  by  the  peridental  membranes  and  not  a  register 
of  possible  muscular  exertion.    Only  a  few  instances  have  come 


THE   FORCE    USED   IN   MASTICATION.  163 

to  my  attention  in  which  I  was  satisfied  that  the  full  capability 
of  the  muscles  had  been  registered.  The  most  notable  of  these 
was  a  young  man,  who,  for  some  years,  had  made  a  business  of 
crushing  glass  and  other  hard,  brittle  substances  with  his  teeth, 
as  a  show,  for  a  living.  He  was  a  slender  fellow  with  no  con- 
siderable muscular  strength.  He  could  register  215  pounds  and 
would  stop  at  that  every  day  very  precisely  in  each  trial  for  a 
week.  He  claimed  stoutly  that  he  used  all  the  muscular  power 
he  was  capable  of  without  the  slightest  pain  about  the  teeth.  I 
am  inclined  to  believe  his  statement.  He  was  much  chagrined 
to  find  others  registering  more  pounds  than  he,  "a  professional 
hard  biter,"  could  do. 

The  strength  of  the  teeth  is  ample  for  all  the  stress  that 
is  brought  against  them,  provided  very  hard  substances  are 
excluded,  such  as  the  harder  metals,  pebbles  and  similar  things. 
This  is  made  clear  by  trials  of  the  strength  of  freshly  extracted 
teeth.  These  were  cut  squarely  off  at  the  junction  of  the  middle 
and  gingival  third  of  the  crown,  so  that  the  occlusal  portion 
would  stand  solidly  on  a  flat  piece  of  steel,  and  arranged  in 
a  registering  dynamometer.  Figures  164,  165.  Then  a  steel 
point  with  a  squared  end  was  applied  directly  to  the  cusp  and 
pressure  slowly  turned  on.  Another  test  was  made  in  the  same 
way,  except  that  a  slip  of  hard  vulcanized  rubber  three  thirty- 
seconds  of  an  inch  thick  was  interposed  between  the  steel  point 
and  the  cusp  of  the  tooth. 

Tests  with  hard  steel  directly  applied. 

(1.)  Mesio-buccal  cusp  of  an  upper  second  molar ;  a  fairly 
sharp  cusp.  A  portion  of  the  enamel  of  the  buccal  portion  of 
the  cusp  split  away  at  125  pounds. 

(2.)  A  rather  obtuse  lingual  cusp  of  the  same  tooth.  The 
enamel  checked  over  a  small  area,  and  the  tooth  not  otherwise 
broken  with  a  stress  of  350  pounds. 

(3.)  Disto-buccal  cusp  of  an  upper  second  molar,  rather 
sharp.  The  enamel  began  to  check  at  135  pounds,  and  a  part  of 
the  cusp  split  off  at  165  pounds. 

(4.)  A  well-rounded  lingual  cusp  of  an  upper  first  bicuspid. 
A  check  in  the  enamel  began  to  show  at  100  pounds,  but  no 
further  break  occurred  with  350  pounds.  On  removing  the  tooth, 
the  enamel  was  found  disintegi'ated  over  a  small  area  where 
the  steel  was  applied. 

(5.)     A  sharp  buccal  cusp  of  an  upper  first  bicuspid.    A 


164  PATHOLOGY    OF    THE    HAJRD    TISSUES   OF    THE    TEETH. 

check  in  the  enamel  began  to  show  at  125  pounds  and  the  buccal 
portion  of  the  enamel  split  off  at  150  pounds. 

(6.)  The  disto-lingual  cusp  of  a  lower  first  molar.  The 
mesial  portion  of  the  tooth  had  been  destroyed  by  caries.  A 
check  in  the  enamel  began  at  115  pounds,  and  the  cusp  crushed 
at  150  pounds. 

(7.)  A  sharp  disto-buccal  cusp  of  a  lower  second  molar. 
A  check  began  at  100  pounds,  and  a  part  of  the  enamel  split  off 
at  140  pounds. 

(8.)  A  lingual  cusp  of  an  upper  third  molar.  A  check  was 
seen  at  100  poimds,  and  a  part  of  the  enamel  chipped  away  at 
140  pounds. 

Tests  with  vulcanized  eubber,  three  thiety-seconds  of  an 

INCH  THICK,  between  THE  STEEL  AND  THE  CUSP  OF  THE  TOOTH. 

(9.)  A  fairly  sharp  buccal  cusp  of  an  upper  first  bicuspid. 
No  injury  at  350  pounds,  but  the  rubber  was  cut  nearly  through 

(10.)  A  sharp  mesio-buccal  cusp  of  an  upper  second  molar. 
No  check  appeared  up  to  325  poimds.  At  335  pounds  the  rubber 
suddenly  parted,  letting  the  steel  come  onto  the  tooth,  and  the 
cusp  was  split  off. 

(11.)    The  cusp  of  a  cuspid.    No  injury  at  350  poimds. 

(12.)  Edge  of  a  central  incisor.  No  injury  up  to  240 
pounds,  at  which  point  the  rubber  suddenly  cut  through,  allow- 
ing the  steel  to  be  thrust  against  the  tooth,  which  was  crushed. 

These  few  cases  show  the  strength  of  the  teeth  as  well  as 
many  additional  examples  would  do.  A  hard  substance,  like 
tempered  steel,  bitten  upon  with  full  force,  is  liable  to  check  the 
enamel  or  even  split  off  a  portion  of  a  cusp,  for  the  reason  that, 
with  the  sharply  rounding  surface  of  the  cusp  the  full  pressure 
is  concentrated  on  a  very  small  area  of  the  enamel.  But,  when- 
ever this  is  distributed  to  a  larger  area  of  surface,  as  is  done  by 
a  cusp  sinking  a  little  into  the  hard  rubber,  no  harm  is  done  by 
even  a  greater  force  than  is  ever  used  in  chewing  food.  Indeed, 
the  teeth  have  sufficient  strength  above  that  actually  required, 
so  that,  when  considerably  weakened  by  caries,  they  are  still 
strong  enough  to  withstand  the  full  force  of  the  occlusion  on 
any  substance  used  as  food.  These  may  be  injured,  however, 
by  the  accident  of  catching  a  small  pebble  or  any  very  hard  sub- 
stance that  might,  by  accident,  be  mingled  with  food,  or  by  biting 
upon  the  harder  metals.  Also  the  teeth  are  sometimes,  though 
rarely,  broken  by  catching  unawares  a  lead  shot  or  some  such 
thing  in  such  a  way  that  it  wedges  between  two  cusps  and  splits 


(-.  « -a 

■£—  a 

CJ  «  P 

u  o  Si 

o    .>. 
"  fc>  5 


S  en  ^ 


^^5   4* 

s  s  a* 
crS  !-  be 


-    C    en   4* 
m.E,C  611 


2  >  fci 

C— -J-  o 

4j  o  n 


o  O  A 


THE   FORCE   USED  IN   MASTICATION.  165 

one  off.  A  cusp  that  has  been  weakened  by  decay  may  occa- 
sionally be  wedged  off  in  a  similar  way  by  softer  material,  such 
as  bread  crusts,  but  it  is  rathei  rare  that  a  perfect  tooth  is  broken 
by  any  accident  in  the  mastication  of  food. 

Force  Required  in  the  Mastication  of  Food. 

ILLUSTRATIONS:    FIGURE  166. 

The  force  required  in  the  mastication  of  different  charac- 
ters of  food  is  important  in  this  connection.  Our  artificial  modes 
of  preparing  foods  have  the  tendency  to  render  them  softer  and 
softer  as  so-called  improvements  are  made.  During  recent  years 
these  have  followed  each  other  with  great  rapidity.  In  almost 
every  line  of  foodstuffs,  the  so-called  improvements  have  ren- 
dered them  easier  of  mastication.  I  give  here  a  table  of  the 
force  required  for  the  crushing  of  meats  from  trials  in  1895 
{Dental  Cosmos).  The  instrument  used  is  the  phagodyna- 
mometer.  Figure  166. 

PHAGODYNAMOMETER    RECORDS. 
CRUSHINO   POINT   OP    MEATS. 

Boiled  corned  beef,  nice  and  tender 30  to  35  pounds. 

Beefsteak,  medium  done,  chuck 40  "  60  " 

Beefsteak,  well  done,  chuck 45  "  60  " 

Beefsteak,  rare  done,  very  tender,  loin 35  "  40  " 

Beefsteak,  round 40  "  50 

Beefsteak,  well  done  and  rather  tough 60  "  80  " 

Mutton  chops 30  "  40  " 

Mutton  steak  35"  45  " 

Roast  veal,  tender  and  nice 35  "40  " 

Eoast  loin  of  veal 30  "  35  " 

Eoast  beef   45  "  60  " 

Eoast  beef,  loin 35  "  50  " 

Pork  chops,  loin 20"  25  " 

Eoast  pork  30  "  35  " 

Broiled  ham,  tender  and  nice ' 40  "  60  " 

Cold  boiled  tongue,  central  part 3  "    5  " 

Cold  boiled  tongue,  near  root 15  "  20  " 

The  following  were  selected  by  an  experienced  butcher  as 
the  toughest  of  meats.    Only  pure  muscular  tissue  was  used. 

Cut  from  shank  of  an  old  animal: 

Fried,  rare  done 60  to  80  pounds. 

Fried,  well  done 70  "  90       " 

Cut  from  the  neck 70"  90      " 

Earely  the  needle  reached  100  pounds  before  the  crush 
occurred. 

These  were  made  from  meats  placed  on  sale  within  two 
hours  after  killing  and  generally  used  the  same  day.    This  was 


166  PATHOLOGY   OF    THE    HABD   TISSUES   OF    THE   TEETH. 

the  custom  in  most  of  the  smaller  cities  up  to  the  time  when  it 
was  supplanted  by  the  cold  storage  meats  prepared  by  the  great 
packing  houses,  which  have  now  almost  universally  taken  the 
place  formerly  occupied  by  the  local  butchers.  These  meats 
are  crushed  at  from  one-fourth  to  one-third  less  number  of 
pounds  than  fresh  meats,  and  they  are  sometimes  even  softer 
than  this  figure,  when  tried  with  the  same  instriunent  under 
otherwise  the  same  conditions. 

A  similar  change  to  softer  foods  is  found  in  every  direction. 
Gardeners  are  vying  with  each  other  in  the  selection  and  culti- 
vation of  the  tenderest  vegetables  possible  in  the  effort  to  satisfy 
the  general  demand  of  our  people  for  tender  foods. 

Some  of  the  confections  are  so  hard  as  to  be  dangerous  to 
the  cusps  of  teeth  that  have  become  weakened  by  caries. 

Crystals  of  rock  candy  crushed  at 30  to    50  pounds. 

Lemon  tablets  crushed  at 50  "     70       " 

Hard  candy  (stick),  old,  crushed  at 90  "  120      " 

Hard  candy  (stick),  fresh,  crushed  at 45  "     60       " 

Small  cinnamon  drops  crushed  at 30  "    60      " 

Some  gum  drops  which  were  mashed  out  of  shape  at  twenty 
to  thirty  pounds  offered  great  resistance  when  wedged  in  between 
the  cusps.  Indeed,  it  often  would  happen  that  these  could  not 
be  completely  crushed  with  less  than  250  pounds.  Small  sticks 
of  licorice  offered  similar  resistance.  These  and  similar  articles 
prove  dangerous  to  the  cusps  of  teeth  that  are  weakened  by 
caries,  or  to  bridges  or  artificial  crowns.  In  the  construction  of 
these  great  care  as  to  strength  should  be  used.  Bread  crusts 
are  equally  dangerous.  Indeed,  within  my  personal  observation, 
more  teeth  that  seemed  sufficiently  strong  have  been  broken 
with  bread  crusts  —  and  not  over-hard  crusts  either  —  than 
with  any  other  one  thing.  I  used  sometimes  to  feel  that  persons 
relating  these  accidents  were  not  quite  honest  in  their  state- 
ments, but  when  I  tried  the  bread  and  found  that  it  would  wedge 
in  between  the  cusps  of  the  teeth  and  not  be  crushed  out  with  a 
force  of  350  pounds,  I  changed  my  mind. 

Some  persons  have  objected  to  my  findings  on  a  number 
of  these  points  because  only  the  direct  up-and-down  motions 
were  used  in  tests;  claiming  that  if  the  lateral  or  grinding 
motion  were  used  the  crushing  would  have  been  accomplished 
with  much  less  force,  and  especially  that  if  bread  crusts  are 
first  wet  with  water  or  the  saliva  they  would  crush  easily.  All 
of  this  is  perfectly  correct.  Rock  candy  or  lemon  drops  will  melt 
away  in  the  mouth  if  the  person  does  not  bite  upon  them,  and 


THE    FORCE    USED    IN    MASTICATION.  167 

bread  crusts  will  become  soft.  But  the  trouble  is,  that  people 
will  bite  upon  them  and  bite  very  hard  before  they  have  become 
wet.  Certaiuly  persons  may  use  the  grinding  motion  on  bread 
crusts,  and  these,  being  brittle,  will  crush  easily,  but  the  fact 
is  people  are  not  always  careful  to  do  this.  Therefore,  for  the 
purpose  intended,  the  manner  of  trial  and  the  results  given 
must  stand  as  correct. 

The  dentist  should  give  warning  to  such  of  his  patients 
as  have  had  their  teeth  weakened  by  caries,  about  biting  on  any 
of  those  things  that  are  liable  to  become  wedged  between  cusps 
and  split  them  off.  It  is  his  business  to  know  these  dangers  and 
to  give  the  necessary  instruction  to  bring  his  patients  to  under- 
stand the  nature  of  these  dangers  to  the  teeth.  He  should  also 
guard  weakness  of  cusps  closely  in  his  manner  of  preparation 
of  cavities  and  placing  of  fillings  that  they  may  stand  the 
severest  stress  possible.  All  that  we  have  learned  of  these 
points  urge  this  course  in  the  strongest  terms.  But  those  whose 
teeth  are  perfect  need  no  warnings  against  the  full  use  of  any 
of  the  things  used  as  foods.  They  should  only  avoid  reckless- 
ness in  biting  upon  the  harder  metals,  pebbles  and  things  of  a 
similar  nature,  which  occasionally  are  mingled  with  food  by 
accident.  The  hazelnuts  that  formerly  grew  wild  all  over  the 
Western  States  generally  required  from  150  to  200  pounds  to 
crack  them.  The  boys,  many  of  the  girls,  and  grown  folks,  too, 
used  to  crack  them  with  their  teeth  as  a  regular  habit.  Many  a 
laugh  was  had  on  seeing  a  boy  with  one  of  these  hard  nuts  between 
his  teeth,  all  of  the  muscles  of  his  body  in  tension,  both  hands  on 
the  lower  jaw  helping;  yet  with  all  of  this  effort  no  perfect 
teeth  were  broken.  The  hazelnut  modified  by  cultivation  —  the 
filbert  that  we  get  nowadays,  is  broken  with  less  than  half  the 
force  required  by  the  wild  hazelnuts.  Any  one  whose  teeth  have 
not  been  weakened  by  caries  should  be  able  to  crack  filberts  with 
perfect  freedom.  If  the  peridental  membranes  have  not  become 
weakened  by  failure  of  proper  use,  it  should  be  a  pleasure  to 
chew  the  hardest  of  ordinary  foods. 

The  cleaning  power  of  vigorous  mastication  is  greater  and 
better  than  artificial  cleaning.  It  does  much  for  the  health  of 
the  teeth  and  the  membranes  about  them  and  contributes  to  the 
general  health  and  vigor  of  the  whole  person.  Therefore  it 
seems  to  be  the  duty  of  the  dentist  to  cultivate  this  in  his  com- 
munity by  careful  advice  to  his  patients  as  he  meets  them  pro- 
fessionally whenever  he  observes  that  the  teeth  are  insufficiently 
used. 


168  PATHOLOGY   OF    THE   HABD    TISSUES    OF    THE   TEETH. 


Sensitiveness  of  the  Peeidental  Membranes. 

From  what  has  been  said  of  the  force  that  may  be  used  in 
mastication,  it  has  been  seen  that,  normally,  the  peridental  mem- 
branes are  very  resistant  and  not  sensitive  to  even  very  heavy 
pressure.  But  extreme  sensitiveness  of  these  membranes  is  fre- 
quent as  a  result  of  disease.  This  may  occur  quickly  as  a  result 
of  pericementitis,  which  often  occurs  after  the  death  of  the  pulp 
of  a  tooth.  Within  a  few  hours  this  membrane,  that  could  bear 
from  100  to  200  poimds  without  complaint,  becomes  so  sensitive 
that  the  slightest  touch  upon  the  tooth  causes  intense  suffering 
In  this  condition  any  operation,  such  as  cutting  for  the  opening 
of  a  cavity,  is  prohibited  by  the  intense  pain  produced,  except 
in  cases  when  the  urgency  of  gaining  immediate  access  to  the 
pulp  chamber  of  the  tooth  in  order  to  clear  the  pulp  canals  for 
relief  of  the  condition  is  imperatively  demanded.  Then  the  tooth 
should  be  supported  in  the  best  possible  way  and  the  cutting 
limited  to  the  least  that  will  effect  that  object.  However,  this 
particular  subject  belongs  to  another  department  and  is  men- 
tioned here  only  as  an  illustration  of  the  fact  that  this  normally 
insensitive  membrane  may  quickly  take  on  a  condition  of  extreme 
sensitiveness. 

Forms  of  hypersensitiveness  differing  from  the  above  occur 
in  which  there  is,  apparently,  no  pain  from  ordinary  light  pres- 
sure; yet  any  considerable  pressure,  and  especially  blows  or 
strokes,  upon  the  teeth,  arouse  much  more  pain  than  is  normal 
to  these  membranes.  This  is  due  to  various  causes.  The  con- 
dition is  habitually  overlooked  by  the  patients  themselves  unless 
it  has  been  rapidly  developed,  which  rarely  happens.  It  is 
usually  chronic  from  the  first.  In  many  of  the  cases  there  is 
very  little  that  the  eye  would  detect  as  wrong  about  the  gums, 
the  teeth,  or  the  mucous  membranes.  But  the  teeth  will  not  bear 
the  normal  amount  of  pressure  without  more  or  less  considerable 
pain.  In  other  cases  there  will  be  marked  redness  of  the  gingivae, 
tumefaction  of  the  interproximal  gum  septums  and  a  tendency 
to  bleeding  from  slight  causes.  This  condition,  however,  is  not 
a  necessary  accompaniment.  When  a  patient  is  found  with  peri- 
dental membranes  that  are  tender  to  pressure  on  the  teeth, 
who  complains  of  the  force  of  blows  used  in  filling  teeth,  or  of 
other  necessary  force  used  in  ordinary  dental  operations,  strict 
inquiry  should  be  made  regarding  the  cause  of  this  abnormality. 
Something  has  happened  which  has  prevented  the  normal  use 


THE   FOBCE   USED   IN   MASTICATION.  109 

of  the  teeth,  which  is  necessary  to  the  health  and  strength  of 
the  peridental  membranes. 

Disease  of  the  peridental  membranes  is  now  becoming  a 
far  more  serious  menace  to  the  teeth  than  dental  caries.  Not  by 
greater  frequency  of  occurrence,  but  by  its  greater  destructive- 
ness  when  it  does  occur.  This  is  to  be  guarded  against  as  well 
as  dental  caries.  In  both,  cleanliness  is  the  principal  factor, 
This  is  an  additional  reason  for  inquiry  as  to  cause  of  tender- 
ness of  the  peridental  membranes.  The  cause  will  generally  be 
found  (1)  in  tenderness  of  carious  cavities  which  has  prevented 
proper  use  of  the  teeth  for  a  time,  (2)  actual  beginning  of  dis- 
ease of  the  peridental  membranes  about  the  gingival  margins, 
(3)  tenderness  in  the  apical  space  from  diseased  tooth  pulps  or 
following  the  death  of  the  pulps  of  one  or  several  teeth,  (4)  from 
the  habit  of  bolting  food  without  the  proper  and  normal  masti- 
cation, or  the  adoption  of  articles  of  diet  not  requiring  force 
in  mastication.  Any  one  of  these  causes  may  be  found  by  such 
examination  as  will  exclude  the  others.  Frequently  the  diag- 
nosis is  so  difficult  as  to  require  that  this  plan  of  rigorous  exclu- 
sion be  followed.  Causes  1,  2  and  3  may  usually  be  found  by 
physical  examination,  and  in  any  case  of  difficulty  this  examina- 
tion should  be  rigorously  made.  Cavities  of  decay  sufficient 
to  cause  pain  in  chewing  food,  are  generally  sufficiently  appar- 
ent or  are  well  known  to  the  patient.  The  same  is  true  of  teeth, 
the  peridental  membranes  of  which  have  become  sensitive 
because  of  disease  or  death  of  the  tooth's  pulp.  In  disease  of 
the  peridental  membranes,  the  patient  is  generally  not  conscious 
of  any  cause  for  the  pain  to  pressure,  for  they  have  already 
ceased  to  use  the  teeth  with  vigor. 

When  the  cause  of  the  difficulty  has  been  established,  the 
treatment  becomes  simple,  if  the  condition  is  causd  by  tender- 
ness resulting  from  dental  caries.  Diseases  of  the  peridental 
membranes  beginning  at  the  gingival  margins  will  not  be  dis- 
cussed. If  the  cause  is  found  to  be  teeth  that  have  become  sensi- 
tive to  the  pressure  of  food  in  mastication  due  to  caries,  the  first 
thing  to  be  done  is  to  remove  this  by  temporary  expedients  and 
put  the  patient  in  condition  to  rebegin  the  vigorous  mastication 
of  food.  No  attempt  should  be  made  to  make  gold  fillings  for 
persons  whose  peridental  membranes  are  abnormally  sensitive, 
(1)  because  unnecessary  pain  will  be  inflicted,  (2)  because  the 
operation  can  not  be  so  well  done.  If  there  are  exposed  and 
inflamed  pulps  the  first  thing  to  do  is  to  remove  these  pulps 
and  place  the  patient  in  a  comfortable  condition  by  the  use  of 


170  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

temporary  fillings  of  gutta-percha.  If  the  difficulty  is  from 
alveolar  abscess  in  any  of  its  forms,  the  treatment  of  these  must 
be  done  and  completed  temporarily  with  gutta-percha  fillings. 
These  should  be  good  enough  for  temporary  use,  made  smooth 
and  neat  and  of  such  form  that  the  patient  may  use  the 
teeth  without  difficulty.  If  decays  are  in  proximal  cavities,  the 
greatest  care  must  be  had  that  there  is  ample  space  for  the 
interproximal  gum  tissue  to  resume  its  normal  form,  and  with 
such  interproximal  contact  as  will  prevent  food  from  leaking 
into  this  space.  The  whole  treatment  must  be  planned  with 
the  view  of  freeing  the  gums  and  peridental  membranes  from 
irritation,  restoring  them  to  the  normal  and  giving  the  patient 
the  full  use  of  the  teeth  in  the  mastication  of  food.  The  excava- 
tion and  formation  of  cavities  should  be  ample  for  this  purpose. 
When  the  tenderness  is  very  considerable,  extensions  of  cavities 
and  the  final  finishing  to  form  may  be  left  until  another  time, 
or,  in  cases  less  acute,  this  may  be  practically  completed. 

Wlien  this  has  been  done,  the  patient  should  at  once  go  into 
training  in  chewing  food.  For  this  purpose  many  persons 
should  make  a  more  or  less  complete  change  in  diet.  Nowadays 
people  often  adopt  a  diet  that  does  not  require  the  use  of  the 
teeth ;  when  such  is  the  case,  the  diet  should  be  changed  to  foods 
that  will  give  exercise  to  the  teeth.  This  should  not  be  too  severe 
at  first,  but  the  work  should  be  increased  as  rapidly  as  prac- 
ticable until  full  vigorous  mastication  has  been  established. 
With  the  continuance  of  this  for  a  few  weeks,  the  sensitiveness 
of  the  peridental  membranes  will  have  mostly  disappeared. 
Most  cases  of  extreme  sensitiveness  to  the  mallet  should  be 
watched  to  see  that  the  patient  is  using  all  parts  of  the  mouth. 
Any  hindrances  to  this  should  be  corrected  and  the  treatment 
continued. 

Patients  who  could  exert  only  thirty  pounds  on  the  molars 
without  extreme  pain  have  often  exerted  100  pounds  within 
one  month,  and  150  pounds  within  three  or  four  months.  Any 
person  who  can  give  a  gnathodynamometer  record  of  125  pounds 
will  not  suffer  much  inconvenience  from  such  malleting  as  may 
be  required  for  the  building  of  any  ordinary  gold  filling.  The 
operator  can  then  make  fillings  as  he  pleases  and  do  himself 
and  his  patient  full  justice. 

If  in  the  diagnosis  it  is  found  that  the  patient  has  fallen 
into  the  habit  of  using  a  diet  in  which  mastication  is  not  needed, 
or  has  formed  the  habit  of  simply  patting  food  into  a  bolus  with 


THE   FORCE    USED   IN    MASTICATION.  171 

the  teeth  and  bolting  it,  the  necessary  trainiug  will  be  the  same, 
but  the  preparatory  treatment  will  be  unnecessary. 

In  preparatory  work  of  this  kind  the  utmost  care  should 
be  had  to  see  that  food  does  not  crowd  into  some  interproximal 
spaces  and  cause  pain  or  injury  to  the  gum  septums.  Leaving 
opportunity  for  this  will  often  defeat  the  whole  scheme  of  treat- 
ment. The  key  to  the  whole  matter  is  that  the  patient  shall  find 
that  chewing  food  becomes  a  pleasure. 


172  PATHOLOGY    OF   THE    HAED    TISSUES    OF    TUE   TEETH. 


MANAGEMENT  OF  LIGHT  AND  CARE  OF  THE  EYES. 

The  management  of  light  is  one  of  the  essential  things  in 
operating.  The  light  should  always  fall  fairly  on  the  field  of 
operation  and  this  should  be  the  brighest  light  in  the  room.  In 
localities  in  which  the  weather  is  generally  fair,  the  ofiSce  is  best 
arranged  if  direct  sunlight  does  not  enter;  but  in  some  localities 
where  there  is  much  cloudy  weather  and  many  dark  days,  posi- 
tions with  the  greatest  amount  of  light  will  be  preferable.  Then 
on  bright  days  the  light  can  be  modified  by  window  shades.  Very 
much  may  be  done  for  the  comfort  of  the  eyes  in  the  choice  and 
arrangement  of  the  wall  decorations  of  the  office  and  still  pre- 
serve a  tasteful  color  selection.  The  principal  wall  colors  should 
never  be  bright.  Neither  should  there  be  any  form  of  glaze  on 
the  walls  that  will  reflect  light.  The  worst  possible  arrangement 
for  a  dental  office  would  be  a  full  white  shining  wall.  All  of  the 
ground  colors  should  be  mild  and  subdued  in  tone.  If  bright 
colors  are  desired,  they  should  be  confined  to  a  very  small  amount 
of  surface  in  order  that  they  may  not  affect  in  any  marked  degree 
the  general  tone  of  light  in  the  room.  Still,  it  is  essential  that 
the  light  in  the  operating-room  be  cheerful  and  that  practically 
all  parts  of  the  room  be  reasonably  well  lighted.  But  it  should 
not  be  brightly  lighted. 

The  operating  chair  should  generally  be  lighted  by  a  single 
window.  This  should  be  low  enough,  when  possible,  to  admit 
horizontal  rays  of  light  when  needed,  or  as  nearly  that  as  prac- 
ticable. A  long  window  from  which  a  high  light  may  be  obtained 
is  also  desirable  but  less  important  than  the  low  and  medium 
range  of  light.  If  more  light  should  be  desirable  for  the  room, 
it  is  best  that  it  be  from  a  window  in  the  same  wall  some  distance 
away  on  the  right  side  of  the  chair.  The  shade  for  this  should 
be  so  arranged  that  this  source  of  light  can  be  conveniently 
closed.  In  certain  positions  at  the  chair  such  a  light  will  be  very 
undesirable.  The  operating  window  should  be  furnished  with  a 
shade,  or  two  shades,  by  which  light  can  be  had  from  any  part 
of  the  window  at  will,  shutting  off  any  part  not  wanted  for  the 
particular  operation.  The  single  window  shade  that  may  be  run 
down  from  the  top  and  close  any  part  of  the  window  below, 
obtaining  the  light  entirely  from  above  the  shade,  or  by  running 
it  up  and  obtaining  all  the  light  from  below,  is  generally  suffi- 


MANAGEMENT    OF    LIGHT    AND    CARE    OF    THE   EYES.  173 

cient  for  a  short  or  medium  length  of  window.  But  for  a  long 
window,  two  shades  that  work  independently  of  each  other,  are 
desirable.  One  of  these  may  be  lowered  from  the  top,  the  other 
may  be  run  up  from  below,  enabling  the  operator  to  use  any  part 
of  his  source  of  light  he  may  desire  at  any  moment  and  place  it 
on  his  work  from  high  up  or  low  down.  Direct  sunlight  should 
always  be  shut  out.  The  light  from  the  clear  sky  is  the  most 
desirable  light  for  dental  operations.  In  all  positions  this  should 
fall  directly  upon  the  work,  without  shadows.  The  arrangement 
should  be  such  that  a  bright  light  will  not  fall  in  the  operator's 
eyes  while  actually  engaged  in  any  operation.  In  positions,  at 
the  chair,  right  side  in  front,  or  left  side  in  front,  the  operator's 
back  should  be  to  the  light,  while  it  falls  full  upon  his  work.  In 
positions  right  side  and  left  side  behind,  the  arrangement  of  the 
chair  should  be  such  that,  with  the  inclination  of  the  head  of  the 
operator,  the  eyebrows  will  fully  shade  the  eyes.  There  should 
be  no  windows  in  the  rear  or  to  the  sides  in  any  well-arranged 
dental  office  that  will  throw  light  into  the  eyes  of  the  operator 
in  any  position  that  is  necessarily  assumed  in  operating. 

In  schools  where  many  students  must  be  accommodated  such 
an  arrangement  is  often  impracticable,  but  even  in  these  the 
student  may  generally  manage  to  avoid  having  a  bright  light 
fall  in  his  eyes  by  turning  the  operating  chair  into  a  favorable 
position.  In  offices  unfavorably  lighted  for  these  purposes  much 
may  be  done  with  suitably  arranged  window  shades.  A  shade 
made  to  raise  from  below  will  exclude  rays  of  light  that  come 
from  too  low  a  source,  and  confine  the  inlet  higher  up,  or  an 
upper  shade  may  change  this  to  a  lower  source,  etc.  In  a  room 
with  several  windows,  certain  ones  may  be  closed  by  heavy 
shades  at  certain  times  in  the  day  and  the  light  modified  to  suit 
the  time  or  position  of  the  sun. 

CAEE   OF   THE   EYES. 

The  care  of  the  eyes  should  be  a  constant  factor  in  the  daily 
routine  of  office  practice  or  school  work  in  dentistry.  There  are 
few  callings  that  are  so  taxing  upon  one's  eyes.  Many  men  have 
eyes  just  a  shade  off  in  focus  so  that  long  continued  close  appli- 
cation becomes  tiresome.  This  will  not  occur  readily  if  the 
adjustment  is  exactly  what  it  should  be.  In  any  such  case  the 
exact  nature  of  the  error  in  vision  should  be  found  promptly  and 
remedied  by  artificial  means,  i.  e.,  properly  adjusted  glasses. 
This  will  not  only  conduce  to  comfort  and  accuracy  of  work,  but 


174  PATHOLOGY  OF   THE  HARD   TISSUES  OF  THE  TEETH. 

will  prevent  eye  strain  that  might  subsequently  lead  to  disease 
of  the  eyes,  and  save  much  physical  wear  and  tear.  Such  glasses 
should  be  adjusted  especially  for  the  operating  chair  and  not 
used  elsewhere.  Others  should  be  provided  for  reading  and 
such  work  when  that  is  necessary.  The  light  should  be  suffi- 
cient, but  should  not  be  too  bright.  Too  bright  a  light  for  the 
retina  of  the  eye  to  bear  with  comfort  causes  a  strain  of  the 
muscles  contracting  the  pupil  that  becomes  even  more  tiresome 
than  the  effort  to  see  with  too  dim  a  light.  One  should  carefully 
guard  against  both  extremes.  Either  may  easily  become  injuri- 
ous to  the  eyes.  If  one's  eyes  are  not  good  and  can  not  be  made 
good  by  artificial  aids,  he  should  not  become  a  dentist.  Many 
men  learn  too  late  that  the  care  of  the  eyes  is  one  of  the  most 
important  considerations.  Dentistry  is  especially  trying  on  the 
eyes  because  of  the  exactness  of  vision  required  and  because  of 
the  long  fixation  of  vision  at  a  certain  fixed  distance  that  is 
unnatural  to  the  normal  human  eyes.  The  perfectly  normal  eye 
should  be  at  ease  from  all  muscular  tension  when  viewing  objects 
at  some  considerable  distance,  as  when  walking  or  riding  through 
a  woodland.  To  bring  the  eyes  to  see  clearly  at  the  very  short 
distances  at  which  the  dentist  operates,  two  sets  of  muscles  that 
are  coordinate  in  their  movements  are  put  in  tension  and  are 
held  in  tension  every  moment  of  the  time  actual  operations  are 
progressing.  The  first  of  these  controls  the  focusing  of  the  lens 
of  the  eye  for  near  objects ;  the  second  converges  the  two  eyeballs 
so  that  both  eyes  see  the  near  object.  When  the  eye  is  normal 
and  this  position  is  held  but  momentarily,  it  is  done  with  ease 
and  is  a  perfectly  normal  use  of  the  eyes.  But  to  hold  this  near 
vision  for  many  hours  together  is  an  abnormal  use  of  the  eyes. 
The  human  eye  with  all  its  wonderful  versatility  of  use  was 
never  intended  for  this  fixed  use  on  near  objects  at  distances  of 
from  ten  to  twelve  inches.  Such  a  use  subjects  the  eye  muscles 
to  a  continuous  strain  similar  to  that  which  one  experiences 
when  holding  his  arm  full  length  in  a  horizontal  position  for  a 
considerable  time.  Without  the  relief  that  comes  from  momen- 
tary relaxations  in  looking  up  from  the  work,  changing  instru- 
ments, etc.,  no  person  could  maintain  this  close  vision  very  long 
at  one  time.  The  reasons  for  this  are  precisely  the  same  as  the 
reasons  for  the  inability  to  hold  the  arm  extended  in  the  fixed 
horizontal  position  for  a  long  time  without  the  relaxation  of 
change  of  position. 

The  time  of  life  is  important  in  the  consideration  of  this 
maintenance  of  near  vision.    In  childhood  the  lenses  of  the  eyes 


MANAGEMENT   OF   LIGHT   AND   CAEE   OF   THE   EYES.  175 

are  soft  and  their  forms  are  controlled  by  slight  muscular  effort. 
As  the  person  grows  older  the  substance  of  the  lens  grows  harder 
and  a  continuous  increase  of  muscular  effort  is  required  for  the 
control  of  the  near  focus.  The  boy  or  girl  of  twelve  years  may 
readily  obtain  perfect  focus  at  six  inches  or  even  less.  At 
twenty-five  years  ten  inches  distance  is  required.  At  thirty-five, 
fifteen  inches  and  the  maintenance  of  this  requires  more  and 
more  muscular  effort.  At  this  latter  age  the  dentist  begins  to 
need  help.  This  is  a  statement  of  something  like  averages  for 
normal  eyes.  But  within  the  range  of  normality  considerable 
personal  differences  must  be  allowed.  Some  will  need  help 
almost  from  the  beginning  of  dental  practice,  while  others  will 
be  able  to  go  longer  without  help.  There  are  variations  among 
persons  that  are  so  wide  as  to  become  abnormal,  producing  far- 
sightedness and  near-sightedness,  or  hypermetropia  and  myopia. 
In  hypermetropia  of  considerable  degree  one  is  unable,  or  soon 
becomes  unable,  to  adjust  the  lens  of  the  eye  for  near  vision  and 
requires  the  artificial  lens  for  its  correction  when  young  in  order 
to  use  near  vision  comfortably  and  effectively.  In  case  of  a  very 
considerable  degree  of  myopia,  the  person  may  need  glasses  in 
childhood  to  enable  him  to  see  clearly  even  at  short  distances. 
With  a  mild  degree  of  short-sightedness  one  may  need  glasses 
for  distant  vision  but  may  see  well  at  short  distances  without 
them.  The  slighter  grades  of  these  difficulties  usually  pass  unno- 
ticed until  some  trouble  with  the  eyes  calls  for  an  examination. 
Few  persons  are  absolutely  free  from  imperfections  in  the  sym- 
metry of  the  curvature  of  the  cornea,  known  as  astigmatism. 
This  distorts  the  vision.  It  is  capable  of  correction  by  suitably 
fitted  glasses.  This  should  be  done  wherever  it  is  found  to  pre- 
vent eye  strain  and  its  attending  consequences,  even  though  the 
vision  may  be  regarded  as  perfect. 

The  first  aid  necessary  to  the  person  with  normal  vision  is 
usually  in  the  focusing  of  the  eye.  This  is  done  by  placing  an 
additional  lens  before  the  eye  to  do  a  portion  of  the  focusing, 
relieving  the  muscles.  Only  partial  relief  can  be  given  so  long 
as  the  muscles  focusing  the  lens  retain  their  activity,  for  the 
reason  that  the  muscles  bringing  the  eyeballs  in  position  for 
short  vision  are  coordinate  in  their  action  with  the  muscles  focus- 
ing the  lens.  One  can  not  converge  the  eyes  for  short  vision  with- 
out setting  the  focusing  muscles  in  action  also.  This  adjustment 
of  the  artificial  lens  must  be  such  as  to  balance  the  difficulties 
between  these  two  sets  of  muscles.  Therefore,  for  continued 
relief  as  the  person  grows  older,  a  continued  increase  in  the 


176  PATHOLOGY   OF    THE    HARD    TISSUES    OF    THE    TEETH. 

power  of  the  artificial  lens  is  required  to  adjust  the  balance  of 
muscular  effort. 

Some  persons,  on  a  false  hypothesis,  fight  against  the  use 
of  lenses  as  aids  to  near  vision,  Ibelieving  that  the  habit  contrib- 
utes to  early  changes  in  the  eye.  This  is  incorrect.  The  eyes 
are  relieved  and  made  better.  The  correct  statement  is  that  the 
person  finding  relief  will  continually  find  the  desire  for  it.  He 
should  have  it. 

For  the  near  vision  used  by  the  dentist  both  sets  of  muscles 
may  be  relieved  artificially  to  advantage.  The  movement  of  the 
eyeballs  in  converging  from  distant  vision  to  near  vision  differs 
among  persons,  but  may,  as  a  general  statement,  be  placed  at 
ten  degrees.  If  prisms  are  placed  before  the  eyes  that  will  do 
this  instead  of  requiring  the  muscular  apparatus  to  do  it,  and  if 
combined  with  this  there  is  a  lens  which  gives  the  near  focus  of 
the  eye  without  effort,  the  eyes  may  see  at  ten  inches  at  ease  and 
obtain  a  much  larger  retinal  image  than  can  be  had  with  the 
unaided  eye.  As  a  statement  of  fact,  this  is  literally  true,  but  in 
its  realization  there  are  certain  serious  difficulties  that  must  be 
imderstood  and  avoided.  When  the  eyes  are  adjusted  to  distant 
vision,  the  person  can  not  by  any  effort  adjust  his  eyes  so  that 
he  will  have  divergent  vision  or  crossed  vision.  All  of  these 
movements  are  the  coordinates  of  the  one  effort  —  to  see  —  and 
can  not  be  separated  by  the  will.  One  may  cross  his  vision  by 
an  effort  to  fix  his  eyes  on  an  imaginary  near  point,  but  he  will 
do  it  much  easier  by  placing  his  finger  before  his  eyes.  But  he 
has  no  power  of  will  to  fix  his  eyes  in  divergent  vision.  There- 
fore, if,  by  aid  of  the  prism  and  lens,  the  eye  is  placed  at  ease 
for  near  vision,  there  is  no  power  of  will  to  change  this  into  more 
distant  vision.  The  only  way  in  which  the  person  may  see  at 
a  greater  distance  is  to  remove  these  aids,  or  look  over  them. 
Therefore,  if  these  aids  are  combined,  the  adjustment  must  be 
only  partial,  relieving  in  part  but  giving  some  opportunity  for 
more  distant  vision.  In  this  way  the  dentist  may  have  relief  for 
both  sets  of  muscles  for  his  purposes  at  the  operating  chair.  The 
use  of  the  prism  before  the  normal  eye  must  be  confined  to  use 
in  seeing  small  objects.  The  prism  distorts  all  portions  of  objects 
outside  of  a  small  area  of  central  vision  and  is  therefore  totally 
unfit  for  reading  or  other  work  in  which  any  considerable  form 
is  prominent  before  the  eye.  While  letters  in  the  center  of  vision 
may  be  very  clear,  the  book  page  will  be  very  annoyingly  dis- 
torted. In  the  mouth,  where  there  are  no  straight  lines,  these 
distortions  soon  pass  out  of  notice.    These  combined  aids  must 


MANAGEMENT    OP    LIGHT   AND    CARE   OF    THE   EYES.  177 

be  confined  to  operuting  glasses  or  other  work  of  similar  sraall- 
ness  of  area  in  which  the  outlying  areas  of  distortion  will  not  be 
annoying.  Even  this  annoyance  will  disappear  after  long  prac- 
tice. In  this  I  speak  from  a  clinical  experience  of  forty  years' 
use  of  prisms  in  operating.  In  my  seventies  my  vision  is  as 
good  as  in  my  thirties. 

The  use  of  prisms  is  not  equally  valuable  to  different  per- 
sons. There  is  much  difference  in  the  pose  of  the  eye  muscles 
of  persons  who  are  capable  of  perfectly  normal  vision.  This  is 
best  illustrated  by  comparison  with  a  muscular  pose  that  soon 
destroys  normal  binocular  vision.  A¥hen  the  pose  of  the  muscles 
of  the  eyes  is  abnormal  to  a  degree  that  renders  it  impossible 
for  the  person  to  continue  the  adjustment  for  binocular  vision, 
squint  occurs.  This  is  called  strabismus.  This  may  be  conver- 
gent or  divergent,  i.  e.,  the  eyes  may  be  crossed  or  they  may 
spread  apart.  The  same  thing  to  a  lesser  degree  occurs  in  per- 
sons permanently  capable  of  normal  binocular  vision ;  the  pose 
of  the  muscles  controlling  the  i)ositions  of  the  eyes  may  be  a  little 
abnormal  one  way  or  the  other,  but  by  a  greater  than  normal 
effort  they  succeed  in  doing  the  work.  The  person  with  a  slight 
tendency  to  divergent  strabismus  in  the  pose  of  the  eyeballs  at 
ease  has  much  more  efTort  to  cross  them  for  near  vision  than  he 
who  has  the  opposite  pose  tending  to  cross  the  eyes.  It  is  the 
person  who  has  the  tendency  to  divergence  of  the  eyes  who 
derives  the  most  important  benefit  from  the  use  of  the  additional 
aid  of  wisely  adjusted  prisms. 

It  will  now  be  apparent  that  all  of  this  adjustment  must  be 
brought  about  by  aid  of  the  experienced  oculist  who  has  the 
necessary  apparatus  and  is  skilled  in  making  the  measurements 
upon  which  the  adjustments  of  these  aids  to  vision  are  based. 
There  is  no  other  profession  or  calling  in  which  men  do  so  much 
fine  vision  work  with  binocular  vision  as  in  operative  dentistry. 
The  watchmaker  and  the  engraver  give  up  binocular  vision  and 
use  a  single  magnifying  lens.  The  dentist  does  not.  Therefore, 
the  dentist,  of  all  others,  should  have  the  greatest  care  as  to  his 
eyes  and  make  the  wisest  use  of  the  aids  to  accuracy  of  binocular 
vision.  One  of  his  special  cares  should  be  comfort  of  binocular 
vision  and  the  continued  usefulness  of  his  eyes.  The  skilled 
oculist  should  be  his  helpmate. 


178  PATHOLOGY   OF    THE    HAED    TISSUES   OF    THE   TEETH. 


EXAMINATIONS    OF    THE    MOUTH. 

A  complete  physical  examination  of  the  mouth  and  teeth  is 
a  matter  of  considerable  difficulty.  Every  examination  should 
begin  with  a  cursory  examination  of  the  patient,  in  which  the 
operator  will  learn  the  general  physical  condition  in  such  degree 
as  may  be  necessary.  He  should  notice  the  patient  particularly 
on  first  presentation,  and  it  is  best  for  the  operator  to  see  the 
patient  on  his  or  her  feet  at  the  first  meeting,  noting  the  carriage, 
the  walk  and  step,  and  the  manner  of  speech  carefully,  as  these 
will  often  give  indications  as  to  the  health  and  strength  of  the 
person.  Such  notice  will  also  frequently  be  sufficient  to  deter- 
mine whether  the  patient  is  in  general  good  health  or  general  poor 
health,  facts  that  should  be  known.  Further,  it  may  also  deter- 
mine whether  the  patient  is  at  the  moment  suffering  pain,  and 
give  some  indications  as  to  the  character  of  the  ailment.  In 
greeting  a  patient,  one  should  generally  inquire  as  to  his  or  her 
health  and  whether  it  is  as  good  to-day  as  usual.  This  will  often 
bring  out  information  that  will  direct  further  inquiry. 

Of  course,  up  to  this  point,  the  inquiry  should  appear  simply 
as  the  manifestation  of  interest  in  the  patient  and  the  condition 
of  the  patient,  as  a  friendly  greeting,  but  to  the  dentist  it  should 
be  really  the  beginning  of  an  examination.  When  the  patient  is 
seated  in  the  chair,  a  few  well-directed  words  often  will  put  him 
or  her  at  ease  and  prepared  for  the  examination.  It  is  well,  in 
the  few  words  that  are  said  at  this  time,  to  drop  the  hand  upon 
the  wrist  of  the  patient,  carefully  noting  the  pulse ;  see  whether 
or  not  it  is  normal,  and  note  any  variation  from  the  normal.  If 
the  pulse  is  too  frequent,  it  may  be  caused  by  a  little  temporary 
excitement  upon  first  taking  the  chair.  That  is  usually  easily 
told  by  the  demeanor  of  the  patient.  Otherwise  too  frequent  a 
pulse  may  denote  a  condition  of  fever,  and  then  the  cause  of  the 
fever  will,  of  course,  be  a  subject  of  inquiry.  A  clinical  ther- 
mometer should  always  be  at  hand  to  take  the  temperature. 
Sometimes  a  too  frequent  pulse  may  denote  a  lesion  of  the  heart ; 
if  that  is  suspected,  a  very  careful  scrutiny  of  tlie  pulse  should 
be  made,  and,  if  necessary,  an  examination  to  determine  whether 
or  not  the  heart  lesion  is  so  serious  as  to  require  special  con- 
sideration in  dental  operations.  Sometimes  the  quality  of  the 
pulse  becomes  important.    If  it  passes  under  the  finger  like  a 


EXAMINATIONS    OP    THE    MOUTH.  179 

hard  shot  or  ball  that  is  not  readily  com})ressible,  or  if  it  is 
stopped  by  the  pressure  of  a  second  finger  upon  the  artery  above 
the  one  with  which  the  examination  is  made,  it  would  be  described 
as  a  quick  pulse,  one  in  which  the  pulsation  passes  under  the 
finger  quickly  and  is  gone,  as  distinguibhed  from  the  frequent 
pulse.  A  quick  pulse  may  be  an  infrequent  pulse  or  a  frequent 
pulse. 

The  opposite  of  the  quick  pulse  is  the  slow  pulse,  where  the 
pulsations  may  be  of  the  usual  frequency  but  are  much  longer  in 
passing  under  the  finger.  The  upward  beat  of  the  pulsation 
comes  slowly  and  it  dies  away  slowly,  leaving  but  a  limited  space 
between  the  two,  varying  from  the  normal  in  the  slowness  of 
the  pulsation  in  passing  under  the  finger,  as  contrasted  with  the 
pulsation  that  passes  under  the  finger  quickly  like  a  shot.  Such 
a  pulse  may  be  frequent,  normal  or  infrequent. 

The  quick  pulse  is  apt  to  represent  a  condition  of  general 
tension  or  nervous  excitability,  while  the  slow  pulse,  other  things 
being  equal,  represents  a  languid  condition  of  the  general  system 
and  may  be  induced  by  severe  disease,  but  does  not  otherwise 
appear  prominently  in  the  person's  appearance.  Persons  pre- 
senting either  of  these  extremes  in  the  quality  of  pulse  are  not 
in  good  condition  to  endure  long-continued  painful  operations  in 
the  dental  chair. 

Being  satisfied  as  to  the  general  condition  of  the  patient,  the 
examination  of  the  mouth  should  proceed.  In  doing  this,  it  is 
usually  best  to  so  raise  or  lower  the  chair  to  bring  the  head  of  the 
patient  to  the  proper  height,  with  the  chair  thrown  a  little  bit 
back,  in  a  position  between  that  which  we  would  use  for  opera- 
tions upon  the  lower  and  the  upper  teeth,  in  order  that  both  the 
teeth  of  the  upper  jaw  and  the  lower  jaw  may  be  seen  without 
changing  the  position  of  the  chair.  Then  it  is  best  to  take  the 
position  of  right  side  behind,  and  passing  the  fore-finger  of  each 
hand  into  the  mouth,  one  on  either  side,  raise  the  lips  and  exam- 
ine the  buccal  mucous  membrane  as  far  as  can  be  done  by  the 
eye ;  or  this  may  be  examined  first  on  one  side  and  then  on  the 
other.  One  should  look  particularly  for  any  points  of  swelling 
or  of  abnormal  redness,  and  for  the  openings  of  abscesses  upon 
the  mucous  membranes  of  both  the  upper  and  lower  jaws.  It 
is  best  to  run  the  eye  around  the  teeth,  particularly  noting,  as 
far  as  practicable  with  the  eye,  the  conditions  present,  and  espe- 
cially the  condition  as  to  cleanliness.  This  will  give  the  operator 
a  fair  indication  as  to  the  care  the  patient  is  taking  of  his  teeth. 

A  similar  examination  of  the  lingual  mucous  membranes 


180  PATHOLOGY    OF    THE    HABD    TISSUES   OF    THE    TEETH. 

above  and  below,  and  also  of  these  surfaces  of  the  teeth,  should 
be  made  with  a  mouth  mirror.  In  doing  this,  it  is  well  to  include, 
or  to  make  a  separate  movement  for,  the  examination  by  the  eye 
of  the  occlusal  surfaces  of  the  teeth.  Finally  the  lips  should  be 
raised  and  the  cheeks  retracted,  while  the  patient  closes  the  teeth 
for  the  examination  of  the  occlusion,  whether  it  is  normal  or 
abnormal.  From  this  point  a  close  scrutiny  should  be  made  of 
any  suspicious  points  on  the  mucous  membranes  that  indicate 
the  death  of  the  pulp  of  a  tooth,  or  trouble  arising  about  the 
gingival  margins  of  the  gums  or  the  necks  of  any  of  the  teeth. 
In  this  first  examination  careful  note  should  be  made  of  any  dis- 
colorations  of'the  teeth,  and  whether  these  discolorations  indicate 
the  death  of  a  pulp  or  are  due  simply  to  some  deposits  upon  the 
teeth.  Any  suspicious  places  upon  the  gum  tissue  should  be  gone 
over  with  the  finger,  and  the  sense  of  touch  noted.  One  who  is 
careful  to  do  this  in  the  examination  of  patients  will  soon  find 
that  the  sense  of  touch  will  indicate  disease  about  the  alveolar 
process  and  apices  of  the  roots  of  teeth,  which  does  not  appear 
to  the  eye,  or  will  give  further  information  when  disease  is 
apparent  to  the  eye.  Often  a  blind  abscess  will  exist  at  the  root 
of  a  tooth  and  there  will  lie  no  appearance  to  the  eye  to  indicate 
it,  whereas  the  sense  of  touch  will  indicate  it  very  clearly  after 
some  practice.  Again,  the  condition  as  seen  on  the  gums  may 
give  evidence  of  some  slight  irritation,  while  the  sense  of  touch 
will  reveal  an  extensive  absorption  of  the  alveolar  process. 

The  patient  will  probably  have  mentioned  having  come  for 
a  particular  purpose  that  will  direct  an  examination  for  some 
particular  thing,  but  this  should  be  put  aside  until  this  general 
examination  has  been  made.  However,  if  it  should  at  any  time 
appear  that  the  patient  has  come  in  an  emergency  and  is  the 
patient  of  another  practitioner,  only  such  examination  should  be 
made  as  will  properly  direct  the  treatment  immediately  required. 
The  patient  should  then  be  referred  back  to  the  dentist  who  cares 
for  the  case.  Otherwise  we  suppose  the  care  of  the  case  is  to 
be  undertaken.  If  it  is  on  account  of  dental  caries  that  the 
patient  has  called,  it  will  generally  be  best  to  examine  for  cai'ies 
at  this  point,  but  in  doing  so  it  is  just  as  well  to  have  in  view 
atrophy,  erosion,  or  any  other  of  the  defects  to  which  the  hard 
tissues  of  the  teeth  are  liable,  such  as  white  spots,  pits  in  abnor- 
mal positions,  etc.  In  examining  for  caries,  the  three  explorers, 
a  pair  of  rights  and  lefts  and  one  with  single  curve,  the  mouth 
mirror,  foil  pliers,  cotton  or  spunk,  or  both,  the  water  syringe 
and  warm  water  should  be  at  hand.    Any  deposits  upon  the  sur- 


EXAMINATIONS   OF    THE    MOUTH.  181 

faces  of  the  teeth  should  he  removed  and  tlie  teeth  washed  with  a 
stream  of  tepid  water.  Then  the  surfaces  of  the  teeth  should  be 
gone  over  in  some  definite  order  which  will  bring  the  instrument 
over  each  of  the  surfaces  of  each  and  every  tooth  in  the  mouth. 
Any  cavities  of  considerable  size  will  be  obvious  at  once,  but  a 
closer  examination  than  this  should  always  be  made  —  an  exam- 
ination that  will  reveal  the  beginnings  of  decay  anywhere. 

It  is  not  important  as  to  the  particular  order  of  this  exam- 
ination, so  that  a  regular  order  is  pursued.  We  may  begin  with 
the  buccal  surfaces  and  go  over  them,  passing  the  instrument 
along  the  gingival  border  of  each,  and  also  passing  the  instru- 
ment into  any  pits  that  appear  in  the  buccal  surfaces,  noting 
whether  or  not  there  is  any  softening,  and  whether  the  instru- 
ment catches  or  enters  at  any  point.  This  should  be  done  in  both 
the  upper  and  lower  jaws,  passing  from  side  to  side  around  the 
mouth.  Generally  it  is  best  to  take  the  upper  jaw  and  then  the 
lower,  changing  the  position  of  the  patient  as  may  seem  best. 
The  recognition  of  the  defects  or  disease  of  the  hard  tissues  of 
the  teeth  must  depend  mostly  on  the  knowledge  one  has  obtained 
of  these  by  lectures,  reading  and  practical  observation. 

The  examination  of  the  occlusal  surfaces  should  be  done  in 
the  same  way ;  each  pit  in  each  tooth  should  be  examined  in  suc- 
cession in  both  the  upper  and  lower  jaws  and  the  conditions 
noted.  Next,  the  lingual  surfaces  should  be  examined.  Although 
decay  is  infrequent  upon  the  lingual  surfaces  of  the  teeth,  exam- 
inations reveal  them  sufficiently  often  to  make  this  necessary, 
and  particularly  the  grooves  that  may  occur  upon  the  lingual 
surfaces  of  the  molars  and  pits  upon  the  lingual  surfaces  of  the 
incisors. 

This  leaves  the  proximal  surfaces  to  be  examined,  and  they 
are  very  much  the  most  difficult.  The  discovery  of  incipient 
decay,  or  decay  of  the  enamel  before  the  enamel  rods  have  fallen 
out,  is  difficult  upon  these  surfaces,  without  the  separation  of  the 
teeth  so  that  the  eye  can  assist  in  the  examination.  The  instru- 
mental examination  should  generally  be  made  with  a  delicate 
pair  of  exploring  tines,  with  rather  short  right  and  left  curves, 
that  may  be  slipped  into  the  interproximal  space  from  the  gingi- 
val, with  the  point  turned  against  the  proximal  surface  toward 
the  contact  point  for  the  detection  of  any  roughness  or  break  in 
the  surface  of  the  enamel.  With  a  pair  of  these  every  part  of 
the  surface  of  the  enamel  may  be  explored  very  close  about  the 
contact  between  the  two  teeth.  An  important  aid  may  be  had  in 
this  examination  by  the  passing  of  a  ligature  through  the  contact 


182  PATHOLOGY    OP    THE    HARD    TISSUES    OF    THE    TEETH. 

point  into  the  interproximal  space  and  pulling  it  back  and  forth 
while  holding  it  against  the  proximal  surface  of  first  one  and 
then  the  other  tooth.  Usually  the  practiced  hand  will  discover 
any  roughness  by  the  drag  of  the  ligature.  Often  the  sharp 
edges  of  a  very  slight  break  in  the  enamel  will  cut  the  ligature. 
It  often  happens  that  a  slight  decay  will  be  discovered  in  this 
way  that  has  been  passed  by  the  exploring  tines.  In  cases  where 
great  precision  is  required,  the  teeth  should  be  cleaned  thor- 
oughly and  the  rubber  dam  put  on  and  then  the  teeth  dried  for 
this  examination.  In  some  cases  it  will  be  necessary  to  use  the 
separator  and  separate  the  teeth  at  some  one,  or  several,  points 
in  order  to  be  satisfied  as  to  the  condition.  At  every  point  where 
the  instrument  catches  or  there  is  a  roughness  that  gives  a  sus- 
picion of  decay,  a  special  examination  should  be  given  that  par- 
ticular point.  The  teeth  should  be  cleaned  and  dried,  and  the 
whitening,  if  any,  noted,  or  any  color  that  is  off  from  the  normal. 
In  this  way  the  amount  of  beginning  caries  of  the  enamel  may  be 
determined,  but  without  this  cleaning  and  drying  it  is  almost 
impossible  to  be  sure  of  the  extent  of  the  injury  or  whether  the 
injury  is  caries  or  some  other  form  or  roughening  of  the  surface. 

Caries  of  the  enamel  that  has  whitened  the  surface  always 
needs  immediate  attention,  either  in  the  way  of  filling  or  in  clean- 
ing. Cleaning  by  the  patient,  properly  directed,  may  often  be 
successful  in  stopping  decay  in  the  enamel  of  the  buccal  surfaces, 
but  on  proximal  surfaces  the  patient  can  not,  by  anything  he  can 
do,  prevent  the  progress  of  the  decay  that  has  once  begun.  The 
only  recourse  now  known  to  us  is  the  filling  of  such  decays,  and  it 
is  much  the  better  plan  to  fill  them  very  early,  while  the  cavities 
may  be  shallow,  not  penetrating  much  into  the  dentin. 

A  dark  color  appearing  in  pits  does  not  necessarily  indicate 
decay.  It  may  be  simply  some  dark  deposit,  and  very  generally  a 
dark  deposit  indicates  a  condition  of  immunity;  yet  it  is  the 
wisest  plan  to  always  try  such  pits  with  the  explorer,  for  it  occa- 
sionally happens  that  a  dark  spot  is  covering  a  decay  that  is 
making  progress  and  should  receive  attention.  As  a  general  rule, 
pits  should  not  be  cut  out  nor  filled  unless  there  is  some  tangil)le 
indication  of  actual  softening  of  the  dentin  beneatli.  If  there  is 
caries  of  the  dentin,  however,  a  filling  should  always  be  placed  at 
the  earliest  practicable  moment  before  great  injury  to  the  dentin 
has  occurred,  keeping  in  mind  continually  the  principal  object  of 
keeping  cavities  as  shallow  as  possible. 

With  this  brief  description  of  the  process  of  examination  for 
caries,  one  who  has  studied  carefully  the  subject  of  caries,  as 


EXAMINATIONS    01''    THK    MOUTH.  183 

presented,  should  be  able  to  make  a  proper  and  sufficient  diagno- 
sis after  some  observation  and  practice  in  maldng  these  examina- 
tions. One  thing  that  is  more  frequently  overlooked  or  passed 
without  sufficient  attention  is  the  lodgment  of  food  between  proxi- 
mal surfaces.  Often  patients  go  to  the  dentist  time  after  time  — 
so  they  relate  —  on  account  of  pain  in  chewing  food,  located 
between  some  two  of  the  teeth,  and  are  assured  that  there  is 
nothing  wrong.  The  fact  that  there  is  pain  from  such  cause  is,  in 
itself,  evidence  of  something  wrong  that  needs  immediate  cor- 
rection. 

When  patients  come  suffering  from  pain,  they  usually  know 
the  seat  of  the  trouble  or  cause  of  such  pain,  and  can  relieve  the 
operator  from  any  considerable  trouble  in  making  the  examina- 
tion. But  it  occasionally  happens  that  the  patient  has  no  correct 
idea  of  either  the  location  or  the  cause  of  the  pain.  When  the 
pain  occurs  from  the  penetration  of  caries  at  some  hidden  point 
imknown  to  the  patient,  the  pain  from  irritation  of  the  pulp 
approached  by  the  decay  is  often  referred  to  some  other  point  by 
the  patient,  and  maybe  to  various  points.  It  should  be  remem- 
bered distinctly  that  the  sense  of  touch  is  the  localizing  sense  and 
that  the  pulp  of  a  tooth  has  not  the  sense  of  touch.  Conse- 
quently it  does  not  in  itself  localize  painful  impressions.  If  there 
has  not  been  something,  as  the  knowledge  of  a  cavity,  to  indicate 
to  the  patient  the  location,  it  may  be  referred  to  the  opposite  jaw, 
upper  or  lower,  or  to  any  of  the  teeth  on  that  side  of  the  mouth, 
or  to  points  in  the  neighborhood.  In  that  case  a  search  must  be 
made  for  the  cause  of  the  pain.  If  the  cause  of  pain  is  obscure, 
it  is  important  to  obtain  from  the  patient  as  full  a  history  of  the 
beginning  and  progress  of  the  pain  as  possible.  This  should 
first  be  related  by  the  patient  in  his  or  her  own  way,  without 
question  or  direction  by  the  dentist,  further  than  that  required 
to  bring  out  the  complete  story  of  the  suffering,  the  points  in 
which  should  be  very  carefully  noted.  After  this  story  of  the 
beginning  and  progress  of  the  pain  has  been  made  as  complete 
as  the  patient  can  do,  the  dentist  may  follow  out  any  thought  his 
knowledge  of  disease,  or  that  the  indications  in  this  particular 
case,  may  suggest,  and  obtain  further  information  by  carefully 
directed  questions.  These  should  go  as  far  into  the  history  of 
the  patient  as  the  conditions  brought  out  may  seem  to  require, 
but  when  such  pain  seems  to  be  from  purely  local  causes,  it  is  not 
necessary  to  seek  far  into  the  general  history  of  the  person.  Gen- 
erally pain  referred  continually  to  one  side  of  the  face,  though 
apparently  occurring  at  different  points,  will  be  found  to  be  due 


184  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

to  exposure  of  the  pulp  of  a  tooth  by  decay  in  some  secluded 
locality.  The  chai'acter  of  the  pain  will  indicate,  to  one  who  has 
had  some  experience,  something  as  to  the  nature  of  the  cause. 
Pains  that  are  due  to  inflammation  of  the  peridental  membrane, 
such  as  incipient  alveolar  abscess  and  the  like,  are  usually  accom- 
panied by  soreness  of  the  teeth,  which  usually  separates  them 
quite  sharply  from  inflammation  or  hyperemia  of  the  pulp  of 
the  tooth ;  for  the  sense  of  touch  for  the  tooth  is  in  the  peridental 
membrane.  In  this  case  the  patient  is  able  to  locate  the  cause  of 
pain  definitely.  In  hyperemia  of  the  pulp,  the  pain  is  fitful,  com- 
ing and  going,  and  is  readily  aroused  by  thermal  changes.  The 
patient,  if  he  has  been  observant,  finds  that  hot  or  cold  drinks, 
or  hot  and  cold  foods,  taken  into  the  mouth  arouse  the  pain, 
which  passes  away  in  a  short  time  when  these  are  removed.  This 
character  of  pain  is  almost  always  from  hyperemia  of  the  pulp 
of  a  tooth,  or  it  may  be  from  inflammation  and  suppuration  of 
the  pulp  of  a  tooth  that  has  occurred  from  some  exposure  by  a 
proximal  cavity  that  is  hidden  ])etween  the  teeth,  or  a  cavity 
that  has  become  covered  by  some  fold  of  the  gum  about  the  gin- 
gival margins.  This  latter  will  usually  be  indicated  by  a  redness 
of  the  gum  at  that  point,  which  will  appear  to  the  ej^e,  or  a  flab- 
biness  that  will  be  told  Ijy  the  touch  when  the  finger  is  passed  over 
it,  either  of  which  will  lead  to  an  instrumental  examination 
revealing  the  facts. 

In  examinations  of  this  character,  it  must  be  remembered 
that  hyperemia  of  the  pulp  may  occur  in  a  tooth  that  is  perfectly 
sound  and  normal  in  every  other  respect.  It  may  have  been 
aroused  by  ice  water,  by  a  blow,  by  catching  something  between 
the  teeth,  or  in  many  ways  that  will  be  very  difficult  to  find  from 
anything  that  will  appear  in  the  examination  or  that  the  patient 
can  tell,  but  the  fact  that  warm  or  cold  water  will  arouse  pain  in 
the  particular  tooth  is  usually  sufficient  to  determine  a  condition 
of  hyperemia  of  the  pulp.  In  a  few  cases  an  inflammation  of  the 
peridental  membrane  of  low  degree  has  been  found  to  show  con- 
siderable thermal  sensitiveness  that  serves  to  confuse  one  in  this 
examination,  but  such  a  condition  is  rare  and  has  usually 
occurred  in  teeth  from  which  tlie  pulp  has  recently  been  removed. 

It  is  also  well  to  remember  that  some  forms  of  neuralgia 
occurring  about  the  jaws  simulate  a  condition  arising  from 
exposure,  or  hyperemia  of  the  pulp,  very  closely,  and  it  requires 
a  very  particular  examination  of  the  teeth  to  exclude  diseases  of 
the  pulp  in  determining  a  condition  of  neuralgia.  Often  the  pains 
in  facial  neuralgia  shift  from  place  to  place,  as  much  as  the  pains 


EXAMINATIONS    OF    THE    MOUTH.  185 

from  the  pulp  of  a  tooth  shift,  for  both  are  apt  to  do  this,  l)nt  gen- 
erally the  neuralgia  has  not  the  thermal  sensitiveness  that  occurs 
in  hyperemia  of  the  dental  pulp.  In  neuralgia  the  pain  is  more 
likely  to  be  excited  by  some  movement  of  the  jaws  or  touch  upon 
the  tissues  of  the  face  or  gums.  It  is  occasionally  very  difficult 
to  arrive  at  a  final  judgment  between  these  two  causes  of  pain. 

The  diagnosis  of  erosion  must  be  made  by  following  the  indi- 
cations given  in  the  presentation  of  that  subject.  The  diagnosis 
of  atrophy  becomes  so  simple  after  one  has  seen  a  number  of 
cases  that  it  is  readily  made  by  following  the  indications  given 
in  the  treatment  of  that  subject.  Pits  appearing  in  abnormal 
positions  in  the  enamel  of  the  teeth  should  be  very  easy  of  deter- 
mination as  to  their  character  after  a  few  of  these  have  been 
noted.  They  generally  require  no  especial  attention  unless  decay 
has  actually  started  in  them. 

Although  the  treatment  of  pathological  conditions  of  the 
dental  pulp  and  of  the  peridental  membranes  are  not  included  in 
the  scope  of  this  book,  the  recognition  of  these  conditions  is  nec- 
essary in  determining  the  course  to  be  pursued  in  filling  teeth, 
and  for  that  reason  their  determination  is  necessary. 

In  all  cases  the  condition  of  the  gingival  margins,  or  free 
margins  of  the  gums,  which  overlap  the  gingival  portion  of  the 
enamel,  should  have  careful  attention,  because  of  the  frequency 
of  disease  beginning  at  this  position,  which  rapidly  diminishes 
the  strength  of  the  peridental  membranes.  Any  abnormal  condi- 
tion of  these  parts  that  may  appear  to  the  eye,  or  of  sensitiveness, 
should  lead  to  close  scrutiny.  In  this  it  must  not  be  forgotten 
that  there  may  be  an  abnormal  degree  of  sensitiveness  of  the 
peridental  membranes  that  arises  from  lack  of  use  of  the  teeth. 
This  is  generally  common  to  all  of  the  teeth.  The  conditions 
found  vary  considerably : 

(1.)  There  may  be  a  slight  swelling  of  the  festoons  of  the 
gingivae  between  two  or  more  teeth,  while  all  other  parts  of  the 
gum  tissues  are  normal.  In  many  cases  this  will  be  found  to  have 
been  caused  by  leakage  of  food  into  the  interproximal  space  in 
chewing  food,  and  demands  such  examination  as  will  reveal  the 
cause  and  lead  to  its  correction.  Neglect  of  this  condition  even 
in  cases  in  which  the  patient  makes  no  complaint  of  pain  from 
lodgments  of  food,  often  leads  to  serious  conditions. 

(2.)  There  may  be  a  general  redness  of  the  gingivse  arising 
from  some  morbid  systemic  condition,  usually  of  little  moment, 
the  correction  of  which  generally  requires  little  else  than  careful 
cleaning  until  the  general  condition  causing  it  passes  away.    It 


186  PATHOLOGY    OF    THE    H.4ED    TISSUES    OF    THE    TEETH. 

is  very  generally  temporary.  Such  a  condition  occasionally  fol- 
lows the  use  of  mercury,  iodin  and  some  other  medicines  that 
affect  these  parts  prominently.  In  filling  operations  during  the 
continuance  of  such  a  condition,  the  peridental  membranes  are 
apt  to  be  more  sensitive  than  normal  to  the  mallet. 

(3.)  Hypertrophy  of  the  gingivae,  in  which  occasionally 
much  thickening  occurs,  covering  much  more  of  the  gingival  por- 
tion of  the  crowns  of  the  teeth  than  normal. 

(4.)  Recession  of  gum  about  the  necks  of  the  teeth  on  the 
labial  surfaces,  often  without  other  appearance  of  disease,  but 
sometimes  with  a  surrounding  area  of  inflammation.  This  occurs 
most  frequently  on  the  cuspids,  upper  or  lower. 

(5.)     Simple  gingivitis  of  local  origin. 

(6.)  Calcic  inflammation  of  the  gums  and  peridental  mem- 
branes. This  is  a  result  of  deposits  of  salivary  calculus  close 
against  the  free  margins  of  the  gums,  or  serumal  calculus  under 
the  free  margins.  If  such  calculus  is  removed  before  consider- 
able injury  has  been  done  and  carefully  kept  from  accumulating 
again,  no  considerable  harm  results.  If  neglected,  the  peri- 
dental membranes  may  be  destroyed  and  the  teeth  lost. 

(7.)  Inflammation  beginning  at  the  gingival  border  of  the 
peridental  membrane,  with  pus  forming  and  destroying  the  mem- 
brane in  the  form  of  pockets  extending  lengthwise  the  roots  of 
the  teeth.  (Phagedenic  pericementitis.)  This  form  of  disease, 
when  once  established,  is  so  difficult  to  cure  that  the  most  careful 
examination  shoiikl  be  made  in  cases  in  which  there  is  reason  to 
suspect  disease  of  these  membranes.  In  phagedenic  pericemen- 
titis, pus  is  generally  exuded  from  about  the  gingiva?  by  pressure 
of  the  finger  over  the  part,  but  is  sometimes  not  clearly  observ- 
able. The  peridental  membrane  and  alveolar  process  is  slowly 
destroyed,  usually  in  tlie  form  of  deep  pockets,  which  may  be 
found  by  exploration  with  a  smooth-end  flat  blade,  otherwise 
similar  in  form  to  the  push  scalers.  These  are  generally  confined 
to  one  side  of  the  root  of  the  tooth,  as  the  proximal,  lingual, 
labial,  or  buccal,  until  very  considerable  progress  has  been  made, 
and  there  is  a  general  tendency  for  the  tooth  to  move  away  from 
the  diseased  side.  Often  when  a  pocket  forms  on  the  proximal 
side  of  the  root,  the  teeth  will  separate  a  little;  if  on  the  lingual 
side  of  the  upper  incisors,  the  teeth  will  protrude,  etc.  When 
such  movements  of  the  teeth  are  observed,  one  should  expect  to 
find  disease  of  this  form.  In  the  mind  of  the  general  profession 
these  different  forms  of  disease,  beginning  at  the  gingivas,  seem 
to  be  confused  under  the  term  "Pyorrhea  Alveolaris."    Any  of 


EXAMINATIONS    OF    THE    MOUTH.  187 

these  conditions  may  be  controlled  if  taken  in  time ;  if  neglected, 
the  last  two  named  tend  directly  to  the  destruction  of  the  peri- 
dental membranes  and  the  loss  of  the  teeth. 

(8.)  Lateral  alveolar  abscesses,  occurring  on  the  sides  of 
the  roots  of  teeth,  the  pulps  of  which  are  alive,  usually  occur  in 
connection  with  phagedenic  pericementitis.  More  rarely  such  an 
abscess  may  occur  from  accidental  causes,  and  then  will  usually 
heal  promptly  when  the  pus  is  discharged. 


188  PATHOLOGY    OF    THE    HARD    TISSUES    OF   THE   TEETH. 


TREATMENT    OF   DENTAL   CARIES. 

In  what  is  said  in  this  volume  of  the  treatment  of  dental 
caries,  attention  will  be  directed  to  general  principles  of  the 
plans  that  may  be  employed  for  its  prevention,  and  for  its  erad- 
ication and  cure,  the  management  of  cases  and  classes  of  cases 
in  combating  pathological  conditions,  and  the  discussion  of  pro- 
phylactic measures  that  may  be  used  by  patients  themselves. 
The  technical  procedures  in  filling  teeth  are  fully  presented  in 
the  second  volume.  No  discussion  of  methods  of  operating  will 
be  given  here. 

Phophylactic  Treatment  of  Caries  by  Artificial  Cleaning. 

If  the  local  conditions  surrounding  the  beginnings  of  caries 
of  the  enamel  and  controlling  its  localization  are  as  have  been 
represented  in  preceding  pages,  and,  if  it  also  be  true  that  with- 
out these,  or  equivalent  conditions,  the  beginnings  of  caries  would 
not  occur,  which  all  logical  consideration  of  the  conditions  seem 
to  declare,  the  first  inquiry  as  to  treatment  should  be  directed  to 
the  question  of  the  possibility  of  preventing  the  beginning  of 
caries  of  the  enamel  in  susceptible  localities  by  systematized 
methods  of  periodical  removal  of  all  deposits.  In  the  consider- 
ation of  the  beginnings  of  decay  of  the  enamel,  the  natural  jjroc- 
esses  of  the  cleaning  of  the  teeth  by  the  mastication  of  food  have 
been  pointed  out  in  brief  and  its  limitations  cited  in  connection 
with  Figures  101-103,  inclusive.  This  shows  that  the  points  of 
failure  of  cleaning,  in  the  chewing  of  food,  are  the  points  at  which 
the  beginnings  of  caries  occur.  Then,  if  these  points  could  be 
cleaned  artificially  at  sufficiently  short  intervals,  dental  caries 
ought  to  be  prevented.  The  proposition  that  dental  caries  never 
begins  on  a  clean  surface  of  any  tooth  is  old,  and  all  modern 
research  tends  strongly  to  support  and  to  strengthen  it.  It  there- 
fore seems  certain  that  if  such  parts  of  every  tooth  as  have  been 
indicated  could  be  kept  clean,  dental  caries  would  be  banished. 
From  time  to  time,  propositions  looking  to  the  cleaning  of  every 
part  of  every  tooth  at  frequent  stated  intervals  in  order  to  pre- 
vent caries  have  been  made.  Most  of  these  have  also  had  in 
them  some  form  of  medication  applied  to  the  surfaces  of  the 
teeth  accompanying  the  cleaning.    Recently  Dr.  D.  D.  Smith  has 


TREATMENT    OF    DENTAL    GABIES.  189 

revived  this  idea  in  its  simpler  form,  relying  wholly  on  artificial 
cleaning  for  results.  This  work  consists  in  the  cleaning  and 
polishing  of  every  part  of  every  tooth  with  fine  pumice,  or  some 
similar  grit,  finishing  with  a  finer  powder.  The  powders  are  used 
on  orange-wood  sticks,  or  similar  material,  cut  in  forms  to  reach 
any  and  all  parts  of  the  teeth.  Very  thin  slips  of  wood  and  strips 
of  tape  are  used  for  the  proximal  surfaces  and  to  pass  the  contact 
points. 

As  a  proposition,  there  can  be  no  doubt  of  its  effectiveness 
if  it  can  be  carried  out  regularly  at  sufficiently  short  intervals, 
but  to  clean  in  this  way  every  part  of  every  tooth  is  not  necessary. 
The  plan  has  in  it  only  the  mechanical  effect  of  cleanliness,  and 
in  susceptible  persons  it  would  appear  that  the  cleanings  would 
necessarily  be  very  frequent  to  effect  the  desired  result.  No 
sufficient  experience  has  yet  been  had  with  this  treatment  that 
will  determine  its  necessary  frequency  in  any  possible  classifica- 
tion of  cases.  Neither  has  it  been  shown  that  patients  will  have 
the  fortitude  to  present  themselves  for  treatment  at  sufficiently 
regular  intervals  month  after  month  and  year  after  year  to  ren- 
der this  method  of  treatment  effective.  It  will  require  years  of 
expei'ience  to  determine  these  points,  and  there  is  the  suspicion 
that  failure  of  the  method  will  result  from  inability  to  maintain 
sufficient  enthusiasm  in  patients  to  bring  them  for  treatment  at 
sufficiently  short  intervals  and  with  the  necessary  regularity. 
The  proposition  is  certainly  correct ;  to  carry  out  the  treatment 
is  the  diffix;ulty. 

The  method,  so  far  as  it  is  yet  developed,  has  been  purely 
empirical.  It  should  be  directed  and  simplified  by  a  much  closer 
study  of  the  beginnings  of  caries  of  the  enamel.  This  will  render 
very  much  of  the  labor  now  being  bestowed  upon  it,  by  those 
who  are  developing  this  treatment,  unnecessary.  While  all  parts 
of  the  teeth  should,  of  course,  be  kept  clean,  much  the  greater 
part  of  the  surfaces  may  be  sufficiently  cleaned  by  the  patient  by 
the  brush  and  the  proper  use  of  the  teeth  in  chewing  food.  There- 
fore, the  dentist,  while  directing  the  whole  of  the  work,  may  limit 
his  manipulation  almost  entirely  to  the  points  of  liability  to 
beginnings  of  caries. 

My  own  success  in  the  treatment  of  buccal  and  labial  sur- 
faces by  the  brush  and  water  in  the  hands  of  the  patient,  which 
has  been  mentioned,  has  been  so  uniformly  successful  in  those 
cases  in  which  it  was  done  faithfully,  that  I  have  but  little  doubt 
of  its  success  in  other  positions.  The  difficulty  with  this  plan  is 
in  the  sufficient  control  of  any  considerable  number  of  people. 


190  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

At  present  it  seems  unwise  to  discuss  the  subject  at  length. 
Its  development  belongs  to  the  journals  rather  than  to  books. 

It  must  be  understood  that  treatment  by  filling  should  be 
supplemented  and  supported,  in  all  cases  of  considerable  sus- 
ceptibility to  caries  of  the  teeth,  by  fairly  vigorous  and  healthful 
chewing  of  food  and  by  artificial  cleaning  with  the  brush  in  the 
hands  of  the  patient.  For  this  purpose,  careful  training  of  the 
individuals  should  be  seriously  undertaken  by  the  dentist  with 
the  same  care  that  he  would  bestow  upon  any  operation  he  per- 
forms for  their  relief.  This  should  be  pursued  to  the  minutest 
details  of  the  motions  of  the  brush  necessary  to  do  the  best  work 
in  each  particular  case.  Examinations  should  be  made  at  inter- 
vals to  see  that  regular  and  correct  habits  become  fixed,  so  that 
important  points  will  not  be  neglected  by  errors  in  handling  the 
brush.  This  work  will  prove  prophylactic  in  a  high  degree.  It 
should  entirely  prevent  the  formation  of  the  gingival  third  buc- 
cal and  labial  cavities.  Even  in  cases  of  marked  whitening  of  the 
enamel  in  several  teeth,  my  experience  shows  plainly  that  the 
decay  of  the  enamel  can  be  effectively  checked  in  any  case  in 
which  the  enamel  has  not  been  penetrated.  The  brush  and  water 
are  all  that  are  needed,  but  these  must  be  correctly  used  to  be 
effective.  Thus  far,  prophylactic  work  done  in  this  way  will  be 
successful.  If  coupled  with  careful  watching  for  special  periods 
of  increased  susceptibility,  frequent  examinations,  or  a  special 
effort  directed  to  treatment  locally  to  prevent  injury  to  the  teeth, 
great  good  will  be  done. 

Treatment  of  Dental  Caries  by  Fillings. 

ILLUSTRATION:  FIGURE  167. 

After  decay  has  once  begun  in  the  dentin  of  a  tooth,  the  onlj' 
treatment  that  has  thus  far  been  found  effective  in  preventing 
its  progress  or  in  curing  the  decay  has  been  the  complete  removal 
of  all  of  the  carious  area  and  the  filling  of  the  cavity  with  metal, 
or  with  some  substance  that  is  durable.  Thus  far,  gold  holds  the 
first  place  for  filling  teeth,  amalgam  the  second  place,  and 
recently  porcelain  and  gold  inlays  are  demanding  important  con- 
sideration. There  are  a  few  persons  who  would  also  give  tin  an 
important  place.  Besides  these  there  are  in  use  gutta-percha 
and  the  cements ;  these  latter  more  especially  for  temporary 
fillings.  In  this  treatment  we  would  seem  to  be  violating  some  of 
the  general  principles  of  physiology  and  pathology.  Certainly 
we  can  not  place  any  of  these  substances  in  the  soft  tissues  with- 


TREATMENT    OF    DENTAL    CARIES.  191 

out  causing  more  or  less  irritation ;  there  will  be  a  reaction 
against  the  presence  of  a  foreign  body,  whether  it  be  in  the  soft 
tissues  or  in  bone.  Any  plug  that  we  may  place  in  a  living  bone 
will  be  loosened  by  absorption  about  it  within  a  short  time.  If 
we  drill  into  bone  for  the  purpose  of  attaching  apparatus  for 
holding  the  ends  of  a  fractured  bone  together  and  fasten  gold, 
silver,  iron,  or  what  not,  into  the  bone  and  apply  force,  we  find 
that  they  will  hold  for  only  a  short  time ;  absorption  will  occur 
about  them  and  they  will  be  loosened.  In  the  teeth  it  is  different. 
No  irritation  is  produced  in  the  dentin  by  a  process  of  this  kind, 
except  such  an  irritation  as  is  produced  by  cutting  the  dentinal 
fibrils  in  the  preparation  of  the  cavity.  This  is  manifested  only 
in  the  prodiiction  of  pain.  No  absorption  of  the  dentin  occurs 
about  the  filling.  There  is  no  vascular  system  that  is  interfered 
with;  there  are  no  physiological  changes  occurring  in  the  hard 
tissues  of  the  tooth.  The  only  changes  of  this  kind  occurring  in 
the  teeth  are  the  changes  in  the  sensations,  which  have  been  pre- 
sented, and  these  changes  in  the  sensory  function  do  not  involve 
changes  in  the  hard  tissues  of  the  tooth.  Do  what  we  may,  we 
fail  to  bring  about  any  absorption  of  calcium  salts  or  any  deposit 
of  calcimn  salts  in  the  substance  of  the  tooth.  There  is  all  of  this 
difference  in  the  physiological  conditions  in  teeth  as  compared 
with  the  physiological  conditions  in  lione.  This  enables  us,  by 
the  insertion  of  fillings,  to  make  an  artificial  repair  of  an  injury 
by  caries.  If  we  had  the  same  conditions  as  to  the  circulation,  or 
the  disposition  to  absorption  or  to  inflammation  that  are  mani- 
fested in  bone  through  the  system  of  Haversian  canals,  or  the 
periosteum,  it  would  be  impossible  for  us  to  make  repairs  by  fill- 
ing ;  as  a  matter  of  fact,  if  such  conditions  existed,  fillings  would 
be  unnecessary,  as  the  tissue  would  have  the  power  of  self -repair. 
Absorption  would  occur  and  fillings  would  be  loosened  and 
thrown  out,  the  same  as  such  things  are  loosened  and  thrown  out 
from  the  bone. 

This  much  to  emphasize  the  fact  that  we  are  working  on  a 
special  class  of  tissue,  the  pathological  conditions  of  which  are 
different  fi'om  those  we  find  in  other  parts  of  the  body.  In  other 
words,  the  enamel  and  dentin,  when  laid  down  are  laid  down  once 
for  all ;  they  are  not  changed  afterward  by  physiological  proc- 
esses. 

For  repair  by  filling  to  be  successful,  it  must  be  very 
minutely  done.  It  has  been  said  that  it  is  not  necessary  that  a 
filling  be  water-tight  to  exclude  microorganisms ;  and,  since  we 
have  learned  that  microorganisms  stand  in  a  direct  causative 


192  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE    TEETH. 

relation  to  decay,  some  persons  seem  to  have  the  thought  that 
if  we  exclude  microorganisms  we  necessarily  prevent  recurrence 
of  decay.  This  is  wrong.  In  conditions  of  susceptibility  to  den- 
tal caries,  it  is  necessary  that  fillings  be  absolutely  water-tight. 
A  full  conception  of  what  that  means  is  not  very  easy  to  obtain. 
A  fairly  clear  conception  of  the  size  of  microorganisms  has  been 
obtained  in  the  bacteriological  laboratory.  Eoughly  speaking,  a 
couple  of  thousand  of  them  can  be  laid  in  a  straight  row  across 
the  head  of  a  pin  and  not  fall  off,  and  yet  they  are  large  enough 
so  that  by  the  use  of  the  microscope  and  microscopic  methods 
we  can  see  them,  handle  them,  count  them  and  measure  their 
size.  We  can  not  see  the  molecules  of  water ;  they  are  so  infi- 
nitely smaller  than  microorganisms  that  we  gain  no  real  con- 
ception of  their  size;  we  can  not  see  them,  count  them  nor 
measure  them;  we  have  no  means  of  getting  at  the  size  of  a 
molecule  of  water,  or  a  molecule  of  acid,  or  a  molecule  of  alcohol. 
They  are  infinitely  small.  Yet  we  must  make  our  fillings  so 
perfect  that  a  molecule  of  water  will  not  go  in  between  the  walls 
of  the  cavity  and  the  filling  material ;  that  a  molecule  of  acid 
will  not  go  in ;  because,  if  microorganisms  happen  to  lie  on  the 
margins  of  our  fillings  and  form  acid,  the  filling  must  prevent 
that  acid  from  seeping  in.  It  must  not  only  simply  prevent 
microorganisms  from  going  in,  but  must  also  exclude  the  acid, 
for  if  the  acid  goes  in  it  will  soon  make  room,  by  the  solution  of 
the  calcium  salts,  for  the  microorganisms.  It  will  be  seen  from 
this  again  why  we  should  lay  our  enamel  margins  in  regions  least 
susceptible  to  decay.  But,  do  as  we  may,  the  margins  of  the 
filling  are  the  vulnerable  lines,  and  these  we  must  devise  means 
of  making  tight  enough  so  that  acid  may  not  seep  in  between  the 
filling  and  the  margins  of  the  cavity. 

If  the  walls  of  a  cavity  are  wet,  we  can  not  remove  the  last 
trace  of  water  by  any  pressure  we  can  bring  to  bear  upon  gold 
or  amalgam  placed  against  them.  Capillary  attraction  is  suffi- 
cient to  resist  all  effort  to  remove  the  last  trace  of  the  film ;  after- 
ward, there  will  be,  in  accordance  with  physical  laws,  an  exchange 
of  fluids  in  this  space  whenever  a  different  fluid  or  solution  comes 
in  contact  with  its  margin.  An  action  occurs  similar  to  dialysis, 
which  has  been  explained  in  considering  caries  of  dentin  and  of 
enamel.  In  this  way  a  solution  of  any  acid  upon  the  surface  of 
the  tooth  will  be  exchanged  for  the  water  in  any  such  film. 

The  removal  of  water  from  the  walls  of  cavities  must  be 
done  (1)  by  absorbents;  (2)  by  evaporation;  (3)  by  absorbents 
followed  by  evaporation,  and,  finally  (4)  by  freshly  shaving  or 


Fia.  167 


Fin.  10".  .\  pliotomicingiaph  nf  .sails  ilial.vzid  ti.ini  llic  saliva  lo  soparalo  Ihcni  from  the  gummj' 
material  with  which  thev  are  assoc-iatod.  ami  crystallized  on  n  clean  Rlass.  When  a  eavit.v  that  has 
heen  wet  with  saliva  has  been  dried  by  hot  air,  both  these  crystals  and  the  gummy  substances  of  the 
saliva  arc  left  on  the  walls  of  the  cavity.  They  dissolve  out  after  the  filling  has  been  made,  causing 
a  lealc. 


TREATMENT    OF    DENTAl,    CARIES.  193 

planing  the  surfaces.  Absorbents,  such  as  absorbont  cotton, 
which  has  been  prepared  for  this  purpose,  will  readily  remove 
the  moisture  ahnost  completely,  and  the  last  trace  may  then  be 
removed  by  evaporation.  But  the  fluid  wetting  such  a  surface  is 
seldom  pure  water.  The  water  will  carry  something  in  solution 
and  this  something  will  be  left  as  a  film  after  evaporation  of  the 
water.  If  the  cavity  be  wet  with  saliva  instead  of  water,  the 
saliva  will  be  loaded  with  salts  and  mucus,  and,  when  dried,  will 
leave  a  film  of  these  that  will  prevent  contact  of  surfaces.  There- 
fore, in  order  to  obtain  actual  contact  of  surfaces,  it  is  necessary, 
after  all  this  has  been  done,  to  freshly  trim  the  surfaces  of 
cavity  walls  after  they  are  dry  and  immediately  proceed  in  plac- 
ing the  filling  material.  These  are  principles  of  physics  that  the 
dentist  should  understand  well  and  appreciate  their  importance 
in  filling  teeth.  The  serious  mistake  of  drying  a  cavity  with  the 
hot  air  syringe  without  other  cleaning,  when  it  has  been  wet  with 
saliva,  will  be  better  appreciated  by  the  examination  of  Figure 
167,  a  photomicrograph  of  the  salts  dialyzed  from  the  saliva  to 
remove  the  crystallizable  salts  from  the  mucin  and  other  gummy 
material.  For  this  picture  a  very  minute  drop  of  the  water  into 
which  the  salts  of  the  saliva  were  dialyzed,  without  the  least  con- 
centration by  evaporation,  was  placed  upon  an  ordinary  glass 
slide  used  for  mounting  microscopic  objects,  and  allowed  to  dry. 
As  soon  as  it  had  crystallized,  the  photomicrograph  was  made. 
Without  the  dialyzing,  the  gummy  material  in  the  saliva  would 
add  to  the  bulk  of  the  film.  Any  one  may  see  this  residue  by 
placing  a  drop  of  saliva  on  a  clean  glass  and  allowing  it  to  dry. 
When  this  has  crystallized  on  the  wall  of  a  cavity,  it  is  white  and 
can  not  be  seen  because  it  is  of  the  same  color  as  the  tooth  tissue. 
This  gummy  material  and  these  crystals  are  freely  soluble  in 
the  saliva,  and  when  a  filling  is  made  against  them  they  after- 
ward dissolve  out,  making  a  slight  leak,  which  is  an  imperfection. 
Therefore,  after  drying,  these  deposits  must  be  cut  away  and 
then  removed.  This  is  only  one  of  the  points  in  the  extreme  care 
necessary  in  the  treatment  of  dental  caries  by  filling.  Many 
others  belong  more  properly  to  the  technical  procedures. 

Curative  Effect  of  Fillings. 

The  necessity  of  making  fillings  water-tight  in  order  that 
they  may  be  curative  has  been  presented.  Fillings  cure  purely 
and  simply  by  shutting  out  everything  from  contact  with  dentin. 
They  should  be  alcohol-tight,  and  alcohol  will  go  in  where  water 
fails;   acids  will  go  in  where  plain,  pure  water  fails  to  enter. 


194  PATHOLOGY   OF    THE    HARD    TISSUES    OF    THE   TEETH. 

Fillings  are  not  curative  in  the  same  sense  that  vaccination  is 
curative  against  smallpox  —  preventive ;  such  remedies  remove 
the  tendency  to  disease ;  something  of  a  material  nature  is  intro- 
duced into  the  blood  and  cellular  elements  of  the  whole  body  that 
tends  to  counteract  the  disease.  Nothing  of  this  kind  is  done  in 
filling  teeth.  No  systemic  change  is  produced  as  a  direct  effect. 
That  is  to  say,  fillings  do  not  remove  the  tendency  to  caries,  and 
the  curative  effect  of  a  filling  is  literally  no  broader  than  its  out- 
line. However,  the  filling  has  beyond  this  a  prophylactic  effect 
that  is  important,  and  how  far  this  will  extend  will  depend 
directly  upon  the  skill  displayed  in  laying  the  outlines  of  the 
cavity,  shaping  and  finishing  the  filling.  If  the  outlines  are  so 
laid  that  microbic  plaques  cover  it  and  lap  over  its  margins,  it 
will  not  protect  the  area  of  liability;  decay  will  begin  again 
close  beside  the  filling.  The  enamel  margin  is  the  vulnerable  line. 
The  filling  itself,  its  own  area,  if  it  is  made  well  and  of  material 
that  is  durable  in  the  mouth,  as  gold  or  amalgam,  is  invulnerable ; 
it  should  last  a  lifetime.  But  the  enamel  margins  about  it  are 
not  invulnerable.  The  shape  given  the  surface  of  the  filling  has 
much  to  do  with  the  protection  of  its  enamel  margins  and  the 
health  of  adjacent  tissues.  The  enamel  composing  its  margins  is 
soluble  in  acids,  and  if  these  margins  are  laid  in  portions  of  the 
area  of  liability,  decay  is  liable  to  recur  immediately  along  the 
margins  and  the  filling  will  be  rapidly  undermined.  Then,  in 
order  that  we  may  make  this  filling  protective,  we  must  study 
the  area  of  liability  in  which  it  is  placed,  as  has  been  indicated 
numbers  of  times,  and  in  its  preparation  so  lay  the  margins  of 
the  ca%'ity  that  it  will  include  the  vulnerable  portions  of  this 
area.  Remember  always  that  we  do  not  cure  in  the  sense  of 
removing  the  liability,  except  as  we  replace  the  area  of  liability 
with  an  indestructible  material.  It  is  only  in  this  sense  that  fill- 
ings are  curative. 

Fillings  are  prophylactic  in  a  very  much  broader  sense.  A 
filling  replaces  a  cavity  which  afforded  opportunities  for  the  col- 
lection of  material  for  fermentation  and  formation  of  acid  or 
other  noxious  products  of  decomposition.  If  the  contact  point 
is  properly  made  in  proximal  fillings,  the  tendency  to  lodgment 
in  the  interproximal  space  is  removed.  This  affords  a  protection 
to  the  immediate  parts,  to  the  neighboring  gum  tissue  and  to  the 
adjacent  parts.  The  filling  becomes  prophylactic  in  a  very  much 
wider  sense  than  the  local  curative  effect,  because  it  not  only  pro- 
tects the  immediate  surface  liable  to  decay,  but  it  protects  the 
Burrounding  parts  as  well.     It  is  also  prophylactic  in  a  still 


TREATMENT    OF    DENTAL    GABIES.  195 

broader  sense,  in  that  it  gives  the  natural  use  of  the  tooth;  a 
tooth  that  was  sensitive,  a  tooth  that  the  patient  avoided  chewing 
upon,  is  brought  again  into  full  use.  That  full  use  tends  to  the 
health  of  the  part  and  the  whole  side  of  the  mouth.  Patients 
often,  on  account  of  one  sensitive  cavity,  will  avoid  the  use  of 
that  side  of  the  mouth,  chewing  entirely  upon  the  opposite  side. 
Then  disease  is  likely  to  run  riot  upon  the  disused  side.  In  this 
way  a  single  filling,  by  allowing  full  usage  of  the  teeth,  may  serve 
to  protect  and  guard  the  whole  side  of  the  mouth  against  future 
decay  and  against  disease  of  the  gums  and  peridental  mem- 
branes. In  this  sense  the  prophylactic  effect  of  the  filling  is  wide 
and  important.  It  is  also  important  in  a  broader  sense  again  than 
this,  for,  by  giving  the  full  use  of  the  apparatus  of  mastication, 
it  contributes  to  the  general  health  of  the  person;  the  food  is 
more  perfectly  masticated,  is  placed  in  a  better  condition  for 
digestion,  and  the  whole  physical  man  is  benefited  by  the  opera- 
tion. 

What  should  be  considered  a  permanent  filling?  What  do 
we  mean  by  permanent?  This  question  might  be  answered  in 
various  ways.  Possibly  many  dentists  would  regard  a  filling  as 
permanent  if  it  afforded  a  reasonable  protection  for  eight  or  ten 
years,  or  four  or  five  years.  This  would  hardly  be  the  highest 
idea  of  a  permanent  filling.  There  may  be  different  degrees  of 
permanence.  Under  some  conditions  I  should  regard  a  filling 
that  protected  the  teeth  for  two  or  three  years  as  doing  good 
service  under  the  circumstances,  particularly  in  making  fillings 
for  children,  where  the  conditions  under  which  the  operation  is 
performed  are  very  unfavorable.  The  child  movement,  to  say 
nothing  of  the  difficulties  of  self-control  in  the  child,  is  such  that 
operations  are  difficult.  We  sometimes  find  the  equivalent  of 
child  movement  in  those  who  are  no  longer  children,  a  condition 
of  the  nervous  system  in  which  there  is  continual  movement  of 
the  person.  This  becomes  so  annoying  that  it  is  almost  impos- 
sible to  operate  with  accuracy.  We  speak  of  these  as  child  move- 
ments because  they  are  so  common  in  children.  They  seem  hardly 
to  be  voluntary  movements ;  involuntary  movements,  as  it  were, 
but  continuous  or  very  frequent.  Other  conditions,  such  as  gen- 
eral nervousness,  sensitiveness  that  can  not  be  well  overcome, 
etc.,  contribute  to  the  difficulties  of  making  fillings,  and  make  it 
necessary,  upon  occasion,  that  we  make  fillings  that  are  not  the 
best,  because  the  conditions  will  not  allow  of  the  best  operations. 
These  should  hardly  be  regarded  as  permanent  fillings,  and  yet 
they  do  a  service  in  protecting  for  the  present,  with  the  hope  that 


196  PATHOLOGY    OF    THE    HAED    TISSUES    OF    THE    TEETH. 

conditions  will  be  so  improved  that  later  on  better  operations 
may  be  made.  These  are  more  properly  fillings  made  for  tem- 
porary purposes,  but  they  are  very  valuable.  A  filling  that  will 
protect  and  prevent  depth  of  cavities,  even  if  it  does  not  prevent 
the  broadening  of  cavities,  is  valuable  in  protecting  the  deeper 
portions  of  the  tooth  and  the  pulp,  and  later,  a  second  operation 
may  be  made  which  is  broader  and  will  protect  the  area  of  lia- 
bility and  be  permanent.  I  should  say  a  permanent  filling  should 
practically  last  a  lifetime.  A  filling  that  is  made  broad  enough  to 
protect  the  area  of  liabilitj^  is  properly  seated  and  properly  con- 
densed, should  stand.  None  of  us  will  be  able  to  operate  with 
that  perfection  that  will  make  every  filling  really  a  permanent 
filling,  but  a  very  large  percentage  of  fillings  should  last  a  life- 
time, or  until  the  natural  processes  of  wear  have  practically 
removed  them,  and  usually,  when  that  is  the  case,  a  refilling  is 
not  needed.  A  good  many  cases  may  be  seen  where  proximal 
fillings  have  been  made  and  the  wear  of  the  teeth  has  been  exces- 
sive, in  which  practically  the  whole  filling  has  been  removed  by 
the  process  of  wear.  Many  of  these  have  been  made  at  a  time 
when  the  patient  was  in  a  condition  of  extreme  susceptibility  to 
caries. 

The  conditions  under  which  fillings  are  least  likely  to  be 
permanent,  even  when  well  placed,  are  important  for  us  to  con- 
sider. More  fillings  will  fail  when  made  for  children  than  when 
made  for  adults,  even  when  just  as  well  made.  The  conditions 
are  such  that  they  are  not  likely  to  be  as  well  made.  And  in  the 
observation  of  dentists  in  their  practice  and  in  the  observation 
of  their  operations,  it  seems  certain  that  they  do  not,  as  a  rule, 
operate  as  well  for  children  as  they  do  for  adults.  It  requires 
more  force  of  the  mallet  to  condense  gold  to  a  given  density  in 
the  teeth  of  children,  than  in  the  teeth  of  adults.  The  force  of 
a  blow  is  measured,  not  so  much  by  the  momentum  given  the  mal- 
let, as  by  the  resistance  offered  to  the  mallet.  It  is  the  old  story 
told  of  the  Irishman,  who  said,  after  he  had  i"eceived  an  injury 
from  a  fall :  "Shure,  sur,  it  was  not  the  fall  that  hurt  me,  it  was 
shtoppin'  so  quick."  If  he  had  fallen  upon  two  or  three  feather 
beds  piled  on  top  of  each  other,  or  into  a  suspended  netting,  he 
would  have  escaped  injury.  And  it  is  just  so  with  the  blow  of 
the  mallet ;  the  number  of  pounds  condensing  power  in  the  blow 
does  not  depend  so  much  upon  the  momentum  with  which  the 
mallet  strikes,  as  the  resistance  offered.  The  peridental  mem- 
branes of  the  teeth  of  children  are  very  much  thicker  than  the 
peridental  membranes  of  the  teeth  of  adults,  so  that  they  give 


TREATMENT    OF    DENTAL    CARIES.  197 

more,  and  it  really  requires  from  one-tliird  to  one-half  more  blow 
to  produce  the  same  result.  It  is  demonstrable  by  actual  tests 
with  falling  weights,  that  a  little  more  spring  in  the  resistance 
makes  that  difference;  and  it  is  a  difference  that  should  be  very 
carefully  studied  in  order  to  guard  against  the  failures  that  occur 
in  condensing  fillings  in  the  teeth  of  children.  This  less  resist- 
ance, because  of  the  greater  spring  in  the  peridental  membranes 
of  the  teeth  of  children,  is  important.  This  is  one  of  the  diffi- 
culties met  with  in  doing  operations  for  children,  in  addition  to 
the  fact  that  they  do  not  bear  pain  so  well  as  adults.  In  older 
persons  the  conditions  are  better,  the  teeth  are  firmer  in  their 
sockets,  a  blow  counts  for  more,  and  the  percentage  of  success 
in  making  permanent  fillings  should  be  much  greater.  Take 
patients  from  sixteen  to  twenty  years  old  as  compared  with  those 
who  are  older,  and  the  dentist  who  keeps  his  records  as  he  should 
will  find  that  the  proportion  of  cavities  filled  for  the  first  time 
will  average  much  greater  in  the  younger  than  in  the  older  peo- 
ple. Many  more  refillings  will  appear  in  the  records  of  the  older 
persons.  These  represent  failures.  In  a  sense,  however,  such 
failures  are  not  complete,  for,  in  many  of  the  cases,  where  care- 
fully studied,  it  will  be  found  that,  while  the  cavities  have  become 
broader,  increased  depth  has,  in  the  main,  been  pi-evented.  Also, 
some  of  the  percentage  of  failure  can  properly  be  attributed  to 
the  greater  difficulty  of  operating  for  the  younger  persons.  In 
making  fillings  for  the  older  persons,  the  conditions  should  be 
better,  the  patients  will  be  under  better  self-control,  and  fillings 
that  will  be  really  permanent  should  be  very  generally  made. 
But  this  requires  the  development  of  a  high  order  of  skill  in  the 
planning  of  the  work  for  the  protection  of  cavity  margins  and 
exactness  in  its  execution. 

There  will  be  some  patients  who  are  older,  in  whose  teeth 
small  cavities  have  begun,  perhaps,  in  their  teens,  decayed  very 
slowly,  stopped  for  a  time,  until  conditions  of  susceptibility  hav- 
ing come  again,  they  have  decayed  a  little  more,  stopped  for  a 
time  and  then  decayed  a  little  more ;  cavities  that  patients  have 
not  noticed  until  the  occlusal  surface  has  broken  through  and 
made  an  opening  that  the  tongue  discovers,  or  in  which  food 
lodges.  In  such  cases  as  these,  no  man  should  fail.  The  patients 
are  older,  they  bear  operations  better,  the  tendency  to  the  recur- 
rence of  decay  is  almost  nil,  all  the  conditions  are  more  favorable 
for  making  operations  that  are  permanent.  In  fact,  in  many 
such  cases,  any  fillings  that  will  stay  appear  to  protect  the  teeth. 
A  man  does  not  deserve  especial  credit  for  succeeding  in  these 


198  PATHOLOGY    OF    THE    HAED    TISSUES    OF    THE    TEETH. 

cases,  and  yet  it  is  important  that  he  do  his  work  well,  because 
there  may  be  a  return  of  susceptibility  that  will  try  even  these 
fillings  severely.  When  persons  have  come  to  the  adult  age  and 
the  expression  of  immunity  is  apparent  in  the  mouth,  any  tyro 
can  make  fillings  that  will  be  apparently  successful.  That  which 
tries  the  skill  of  the  dentist  is  the  making  of  fillings  which  will 
stand  the  test  of  time  for  the  very  susceptible  child,  with  a  hered- 
itary condition  continuing  this  susceptibility  on  to  maturity. 

Selection  of  Filling  Mateeial. 

In  the  management  of  eases,  the  selection  of  filling  material 
should  have  careful  consideration,  and  this  is  especially  true  in 
the  management  of  families  of  children.  The  plan  of  manage- 
ment should  always  include  this  selection,  and  it  should  be  deter- 
mined early  in  the  consideration  of  each  individual  case. 

Gold  should  always  hold  the  first  place  and  be  regarded  as 
the  material  for  use,  unless  displaced,  for  some  specific  reasons. 
Gold  holds  this  place  because  of  its  intrinsic  merits  as  a  filling 
material  for  the  cure  of  caries,  aside  from  any  consideration  of 
its  expense  or  of  the  popular  consideration  of  its  purity,  inde- 
structibility, or  that  glamour  that  comes  from  its  imiversal  use 
as  money  and  consequent  high  consideration  of  its  value.  These 
points  that  make  so  much  for  the  use  of  gold  in  the  public  mind, 
should  have  little  consideration  by  the  dentist  intrinsically,  and 
yet  these  popular  fads  can  not  be  ignored  entirely  in  our  dealings 
with  the  people.  They  have  their  place  in  the  minds  of  those 
with  whom  we  deal  and  must  be  considered  as  fixed  facts  that 
can  not  easily  be  brushed  aside.  For  these  reasons,  the  dentist 
will  often  be  induced  to  use  gold  in  positions  of  extreme  difficulty 
for  both  himself  and  his  patient,  when  his  own  better  judgment 
would  lead  him  to  use  another  material.  Again,  esthetic  con- 
siderations will  call  for  the  use  of  gold  in  restorations  in  posi- 
tions where  the  filling  can  not  be  hidden,  and  will  call  for  long 
and  tedious  malleting  upon  a  sensitive  peridental  membrane  that 
will  be  in  danger  of  permanent  injury.  In  a  general  practice  it 
will  often  occur  that  such  circumstances  limit  the  power  of  choice. 
This  difficulty,  that  has  been  felt  to  be  very  real  and  trying  in 
the  past,  is  being  much  relieved  by  the  use  of  the  porcelain  inlay 
in  difficult  cases  that  come  in  prominent  view,  and  the  gold  inlay 
in  large  cavities  in  the  molars. 

The  general  rule  should  be  that  gold  should  be  used  for 
young  people  and  for  children,  for  the  reason  that  with  it  the 
placement  can  be  more  accurate  than  with  any  other  material. 


TREATMENT    OF   DENTAL,    GABIES.  199 

and,  therefore,  with  it  the  power  of  limiting  decay  during  the 
period  of  the  more  extreme  susceptihility  is  greater  than  with 
any  other  material.  This  should  not,  however,  lead  the  zealous 
practitioner  to  undertake  the  use  of  gold  under  circumstances 
that  will  prevent  perfect  operating.  It  should  be  remembered 
always  that  gold  is  intrinsically  better  in  limiting  or  curing 
caries  only  because  it  can  be  more  accurately  placed.  If  the  cir- 
cumstances are  such  as  to  defeat  this  accuracy  of  placement, 
another  material  should  be  used  temporarily,  in  case  gold  has 
been  determined  upon,  until  better  conditions  may  be  attained. 

In  the  care  of  families  of  children,  it  will  happen  that  con- 
siderations of  economy  will  require  that  a  cheaper  material  be 
used.  When  this  is  the  case,  the  facts  should  receive  careful 
consideration  and  a  course  of  action  determined.  In  this  the 
greatest  care  should  be  exercised,  and  even  then  it  will  be  impos- 
sible to  avoid  serious  error.  Many  times  it  has  happened  that 
amalgam  was  chosen  for  the  molars  and  bicuspids  of  families 
of  children,  and  when  they  have  grown  to  adults  they  have  been 
greatly  chagrined  because  such  a  choice  had  been  made  for  them. 
Changes  in  financial  conditions  of  families,  and  in  the  mental 
attitude  of  persons  toward  such  matters,  will  inevitably  bring 
some  very  awkward  conditions  and  relations  not  appreciated  by 
the  laity. 

Under  no  circumstances  can  other  than  gold  be  used  for  fill- 
ings in  the  six  front  teeth,  except  inlays  as  indicated  elsewhere, 
and  cement  fillings  as  a  temporary  expedient  under  some  pecul- 
iar conditions.  This  is  to  be  regarded  as  a  law  that  can  not  be 
transgressed  because  of  esthetic  considerations,  except  under 
conditions  under  which  porcelain  inlays  may  be  chosen.  But  in 
the  molars  and  bicuspids,  esthetic  considerations  become  less 
prominent  in  proportion  as  fillings  will  be  hidden  from  view. 
In  these,  amalgam  may  be  used  instead  of  gold,  when  required 
by  the  necessity  of  economy.  Formerly,  I  had  been  much  opposed 
to  the  use  of  this  material  in  the  teeth  of  children  of  very  sus- 
ceptible families  for  the  reason  that  its  power  of  limiting  decay 
was  so  very  much  below  that  of  gold,  but  lately,  since  we  have 
had  more  experience  with  amalgams  that  neither  shrink  nor 
expand,  it  is  found  that  the  curative  power  of  this  material,  when 
carefully  and  intelligently  used,  stands  well  up  toward  that  of 
gold.  This  gives  it  a  much  wider  range  of  usefulness  in  the 
teeth  of  susceptible  young  people  than  formerly. 

Then  if,  through  the  necessities  of  economy,  amalgam  is 
chosen,  it  should  be  limited  to  certain  portions  of  the  mouth,  and 


200  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE   TEETH. 

used  exclusively  in  those  portions  from  tlie  beginning.  This  may 
be  the  molar  teeth  or  the  molars  and  bicuspids.  A  question  that 
I  have  foimd  myself  asking  many  times  in  this  connection  has 
been:  "Will  amalgam  fillings  in  the  mesial  surfaces  of  the 
bicuspids  in  this  mouth  show  a  dark  color  that  can  be  noticed 
in  ordinary  social  intercourse?"  The  answer  to  this  question 
should  have  decided  weight  in  the  choice  of  material  for  these 
teeth,  and  in  young  girls,  particularly  those  with  thin  lips,  light 
complexion  and  active  facial  muscles  that  will,  upon  occasion, 
show  these  teeth  prominently,  esthetic  considerations  should 
debar  amalgam.  It  will  not  do  to  say,  ' '  This  is  only  a  little  girl 
and  the  appearance  is  not  important."  In  a  very  few  years  the 
girl  of  twelve  or  fourteen  is  the  young  lady  of  eighteen,  with  all 
of  the  pride  of  personal  appearance  belonging  to  that  age,  and 
esthetic  considerations  in  case  of  the  younger  girl  should  have 
the  young  lady  in  society  in  view,  and  the  choice  of  filling  mate- 
rial should  be  made  accordingly.  On  the  other  hand,  if  the  lips 
are  thicker,  the  facial  muscles  less  active,  the  teeth  better  covered 
and  the  complexion  darker,  there  will  be  less  objection  to  the  use 
of  amalgam  in  the  bicuspids. 

These  matters  should  be  considered  and  determined  for  each 
person,  and  afterward  there  should  be  no  commingling  hap- 
hazard of  amalgam  and  gold  fillings  in  the  back  teeth.  It  should 
be  all  one  or  the  other  in  the  limits  determined  upon. 

In  older  people,  these  considerations  become  less  important, 
but  are  never  obliterated.  As  a  rule,  they  are  stronger  in  women 
than  in  men,  but  they  never  disappear  at  any  age,  or  in  either 
sex. 

The  use  of  gold  fillings  becomes  limited  in  many  cases  by 
reason  of  disease  of  the  peridental  membrane.  Often  a  very 
little  appearance  of  disease  limits  materially  the  endurance  of 
the  peridental  membrane  under  the  stress  of  mallet  pressure  to 
such  an  extent  as  to  properly  prohibit  tlie  building  of  large  gold 
fillings.  Further,  when  a  very  large  filling  is  to  be  built  in  a 
molar  tooth  and  the  membranes  are  not  particularly  strong,  the 
long-continiaed  malleting  necessary  to  the  proper  condensation 
of  the  gold  is  likely  to  do  permanent  injury.  In  all  such  cases, 
amalgam  or  inlays  become  the  more  appropriate  material.  These 
conditions  usually  occur  at  a  more  advanced  age,  when  the  inten- 
sity of  the  tendency  to  caries  has  become  so  much  modified  that 
the  danger  of  recurrence  of  decay  is  much  less. 

In  the  front  teeth,  amalgam  is  debarred.  In  case  tlie  mem- 
brane has  become  so  weakened  that  gold  can  not  be  used,  it  is 


TEEATMENT    OF    DENTAL    CABIES.  201 

better  to  use  inlays  or  tide  the  case  along  with  cement  fillings, 
renewed,  as  may  be  necessary,  from  time  to  time,  awaiting  better 
conditions. 

In  broken  teeth,  or  teeth  so  badly  decayed  as  to  necessarily 
show  much  gold  in  fillings,  the  question  of  the  use  of  porcelain 
inlays  should  be  considered.  For  the  present,  I  think  it  should 
be  considered  that  the  power  of  arresting  decay  is  low  in  porce- 
lain inlays  set  with  cement,  and  there  should  be  more  caution 
as  to  their  use  in  the  teeth  of  young  persons  who  show  much  ten- 
dency to  caries.  But  when  decided  immunity  to  the  beginning  of 
decay  has  become  apparent,  this  plan  of  lepair  may  serve  an 
excellent  pur^DOse  in  the  restoration  of  lost  parts.  It  is  par- 
ticularly well  adapted  to  the  hiding  of  such  defects  in  the  teeth 
of  singers  and  others  who  are  much  before  the  public  and  in 
whom  such  blemishes  become  especially  prominent. 

Inlays  are  also  very  desirable  in  eases  of  weakening  of  the 
peridental  membranes  in  cases  of  recession  of  the  gums  or  other 
cases  of  injury  to  the  peridental  membranes  of  any  of  the  teeth. 
In  these  cases  the  patients  are  generally  older  and  the  tendency 
to  decay  so  limited  that  the  power  of  protection  from  further 
decay  has  become  less  important. 

The  limitation  temporarily  of  the  use  of  gold  in  young 
patients,  or  in  sensitive  teeth,  awaiting  better  conditions,  will  be 
sufficiently  presented  elsewhere. 

In  case  of  prominent  loss  of  substance  of  teeth  by  wear 
(mechanical  abrasion),  the  material  used  for  repair  or  the  build- 
ing up  of  the  lost  part,  should  be  the  hardest  that  we  can  use  for 
the  purpose.  Generally  the  platinum-gold  foil  shade  No.  3  should 
be  chosen.  This  has  all  the  merits  of  a  pure  gold  filling,  but,  if 
well  condensed,  stands  severe  abrasion  much  better  than  gold 
alone.  There  is  apt  to  be  some  objection  to  this  material  in  the 
minds  of  some  patients  on  account  of  its  color  being  not  that 
rich  yellow  of  pure  gold.  Because  of  this  difference  in  color,  they 
are  apt  to  think  it  an  inferior  material.  This  is  because  the 
public  is  less  acquainted  with  the  value  of  platinum,  and  is,  in 
fact,  a  prejudice.  Or,  better  stated,  the  public  is  not  sufficiently 
acquainted  with  it  for  its  character  and  qualities  to  declare  them- 
selves at  sight  and  it  leads  to  questioning.  It  is  richer  than  pure 
gold,  more  durable  under  abrasion,  its  color  makes  it  less  notice- 
able, and  altogether  it  is  intrinsically  a  better  material  than  gold 
for  all  fillings  that  show  in  the  front  teeth  because  of  its  less 
prominent  color.  As  this  material  can  be  worked  conjointly  with 
pure  gold,  it  may  be  used  simply  as  a  veneer  on  those  parts  of 


202  PATHOLOGY    OP    THE    HARD   TISSUES   OF    THE    TEETH. 

the  filling  that  will  be  seen  from  the  front.  When  used  in  cases 
of  abrasion,  those  portions  of  the  filling  within  the  cavity  proper 
may  be  made  of  pure  gold,  and  all  of  the  body  of  the  filling  that 
will  become  exposed  to  wear,  or  to  view,  made  of  platinum  gold. 


MANAGEMENT   OF   CAVITIES   BY   CLASSES.  203 


.      MANAGEMENT    OF    CAVITIES   BY    CLASSES. 

Under  this  heading  it  is  the  intention  to  discuss  the  relation 
that  the  treatment  of  caries  should  bear  to  the  local  conditions  of 
its  causation,  the  intensity  of  susceptibility  of  the  individual  and 
the  changes  in  susceptibility  and  immunity  which  may  occur  as 
patients  become  older.  This  will  include  the  time  in  the  life  of 
the  individual  of  the  occurrence  of  the  different  classes  of  cav- 
ities and  some  notes  on  recurrence  of  decay  at  unusual  times. 

Classificatidk. 

Class  1.  Cavities  beginning  in  pits  and  fissures  in  any  parts 
of  the  teeth  in  which  these  occur. 

Class  2.  Cavities  beginning  in  the  proximal  surfaces  of  the 
bicuspids  and  molars. 

Class  3.  Cavities  beginning  in  the  proximal  surfaces  of  the 
incisors  and  cuspids  which  do  not  require  the  removal  and 
restoration  of  the  incisal  angle. 

Class  4.  Cavities  beginning  in  the  proximal  surfaces  of  the 
incisors  which  require  the  removal  and  restoration  of  the  incisal 
angle. 

Class  5.  Cavities  beginning  in  the  gingival  third  —  not  pit 
or  fissure  cavities  —  of  the  labial,  buccal  or  lingual  surfaces  of 
the  teeth. 

This  classification  is  especially  intended  for  use  in  technical 
procedures.  But,  as  it  is  also  a  classification  of  cavities  which 
expresses  the  order  in  which  they  most  frequently  occur  in  the 
age  of  the  individual,  it  will  be  of  use  here  in  bringing  the  ques- 
tions at  issue  in  more  orderly  form. 

Caries  of  the  teeth  presents  considerable  differences  when 
occurring  in  different  localities  in  the  mouth  or  upon  different 
surfaces  of  the  teeth,  and  at  different  ages  of  patients  that  call 
for  differences  in  the  management  of  cases.  Occasionally  all 
classes  of  cavities  will  be  found  in  the  same  mouth  and  require 
treatment  at  the  same  time.  This  is  comparatively  rare,  but 
when  it  occurs  in  a  young  person  the  case  is  a  very  grave  one. 
The  rule  is  that  in  very  susceptible  persons,  particular  classes 
of  cavities  make  their  beginnings  at  about  a  certain  time  after 
each  of  the  several  teeth  has  taken  its  place  in  the  arch.  This 
certain  time  will  be  early  or  late  with  different  patients,  accord- 


204  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE    TEETH. 

ing  to  the  intensity  of  the  susceptibility  and  favorable  or  unfavor- 
able local  conditions.  If  the  first  molar  is  found  with  occlusal 
decay  at  eight  years,  two  years  after  it  takes  its  place,  the  second 
molar  is  apt  to  be  decayed  in  the  occlusal  surface  at  fourteen,  or 
two  years  after  it  presents  in  the  arch.  The  same  rule  follows 
in  pit  cavities  in  other  teeth.  If,  however,  the  first  molar  is  not 
decayed  until  twelve,  other  pit  cavities  will  also  be  late  occur- 
ring, and  not  so  many  will  occur.  Pit  cavities  do  not  occur  if 
there  are  no  pits,  but  they  do  not  necessarily  occur  if  there  are 
pits.  The  number  and  the  time  of  their  occurrence  will  be  con- 
trolled mostly  by  the  susceptibility  to  caries  in  the  individual. 

Cavities  of  the  other  classes  occur  at  a  later  date  as  the  rule. 
Therefore,  when  cases  are  closely  followed  with  respect  to  indi- 
vidual teeth,  we  have  to  deal  with  one  class  first,  then  another 
and  then  a  third,  as  our  patient  grows  older.  In  following  the 
history  of  one  hundred  persons,  we  find  beginning  decays  in  the 
first  molars  in  five  distinct  localities  which,  in  a  considerable 
majority,  appear  in  the  following  order  as  to  time:  (1)  In  the 
pits  of  the  occlusal  surface;  (2)  pits  of  the  buccal  surface  (less 
frequent) ;  (3)  in  the  mesial  surface;  (4)  in  the  distal  surface; 
(5)  in  the  gingival  third  of  the  buccal  surface. 

Cases  occur  frequently,  however,  in  persons  twenty-five  to 
thirty  years  old  or  more,  in  which  caries  progresses  so  slowly 
that  when  the  patient  presents  for  treatment  the  several  classes 
of  cavities  may  be  present  at  the  same  time.  These  must  be 
sharply  distinguished  from  cases  in  which  the  different  classes  of 
cavities  begin  very  nearly  together  in  persons  of  fifteen  to  eight- 
een years  old.  In  the  first,  the  intensity  of  susceptibility  has 
been  sufficient  to  start  many  areas  of  decay,  but  the  early  ten- 
dency toward  immunity  has  checked  the  progress,  and  the  case 
is  readily  manageable,  while  in  the  treatment  of  the  second  we 
have  to  deal  with  the  full  intensity  of  the  susceptibility.  Special 
conditions,  which  are  due  to  early  childhood,  will  be  presented 
under  the  heading,  "Management  of  Children's  Teeth." 

Cavities  of  the  First  Class. 

Cavities  of  the  first  class,  in  the  large  majority  of  persons 
met  with  in  practice,  are  first  to  appear.  These  include  pit  and 
fissure  cavities  in  the  molars,  bicuspids,  upper  lateral  incisors, 
and  more  rarely  in  the  upper  central  incisors  also.  In  a  large 
proportion  of  persons,  the  first  of  these  are  in  the  molar  teeth, 
and  in  many  persons  these  are  the  only  cavities  of  this  class,  the 
incisors  being  free  from  pits  and  fissures,  and  decay  not  occur- 


MANAGEMENT    OF    CAVITIES    BY    CLASSES.  205 

ring  in  the  pits  of  the  bicuspids.  Under  equal  conditions  of  sus- 
ceptibility and  local  conditions  among  the  different  teeth,  decay 
in  pits  and  fissures  would  occur  within  about  a  certain  time  after 
the  teeth  take  their  places  in  the  arch.  In  highly  susceptible 
persons  this  will  be  within  from  one  to  three  years,  and  at  a 
later  time  as  the  susceptibility  is  less.  Therefore,  while  this  class 
is  first  to  appear  in  the  individual  teeth,  the  cavities  are  scattered 
over  a  considerable  period  in  the  person,  and,  as  both  the  sus- 
ceptibility and  local  conditions  vary  greatlj^  in  different  persons, 
we  meet  with  this  class  of  cavities  at  various  ages  of  persons.  It 
is  only  through  the  careful  observation  of  records  of  many  per- 
sons that  general  rules  are  made  out. 

The  local  conditions  relate  almost  entirely  to  the  form  and 
depth  of  pits  and  fissures.  Well-closed  pits  rarely  decay.  In 
very  susceptible  persons  decay  begins  early  in  deep  pits  and  in 
fissures.    In  immune  persons,  decay  may  not  occur  at  all  in  these. 

Pit  cavities  in  the  second  molars  begin  to  occur  at  from  four- 
teen to  sixteen,  and  often  make  rapid  progress  in  highly  suscep- 
tible persons.  If  it  is  remembered  that  these  cavities  usually 
appear  in  very  susceptible  families  in  from  one  to  three  years 
after  the  eruption  of  the  teeth,  and  the  order  and  time  of  their 
eruption  is  kept  in  mind,  the  whole  matter  will  be  materially 
simplified  and  the  reasons  for  the  order  of  their  appearance  will 
be  readily  grasped.  One  will  therefore  look  especially  after  these 
teeth  at  the  proper  time.  The  pit  cavities  are  the  simplest  of  all 
cavities  to  treat,  and,  when  taken  in  time,  rarely  present  any 
considerable  difficulty.  It  should  be  remembered,  however,  that 
in  occlusal  surfaces,  the  whole  surface  of  the  fillings  is  fully 
exposed  to  thermal  changes  by  hot  and  cold  drinks  and  foods. 
They  are,  therefore,  in  more  danger  from  thermal  sensitiveness 
in  proportion  to  their  area  than  other  cavities.  In  proximal  cav- 
ities, much  of  the  area  of  the  fillings  is  shielded  by  the  proximat- 
ing  tooth.  In  buccal  cavities  the  fillings  are  not  so  directly  exposed 
to  thermal  changes,  therefore  where  dealing  with  very  deep  cav- 
ities especial  care  should  be  had  to  shield  the  pulp  from  thermal 
changes.  This  is  best  done  by  covering  the  pulpal  wall  with  a 
layer  of  oxyphosphate  of  zinc  and  making  the  filling  over  this, 
after  it  has  become  fully  hard.  Theoretically,  gutta-percha  is 
the  best  non-conductor,  but,  practically,  it  is  too  soft  to  serve  as 
the  support  of  a  permanent  filling  and  should  never  be  used. 

Filling  over  softened  dentin.  There  is  a  practice  among 
many  in  the  profession  of  leaving  a  portion  of  softened  dentin 
in  deep  occlusal  cavities  and  filling  over  it,  claiming  that  when 


206  PATHOLOGY   OF    THE    HAUD    TISSUES   OF    THE    TEETH. 

securely  covered  in,  especially  if  saturated  with  an  antiseptic,  no 
more  decay  will  occur.  This  procedure  is  very  tempting  in  han- 
dling deep  occlusal  cavities.  So  far  as  continuance  of  the  decay  is 
concerned,  the  statement  is  correct,  but  this  carious  mass  con- 
tains a  poisonous  substance  elaborated  during  the  carious  proc- 
ess, which,  when  shut  up  in  this  way,  especially  endangers  the 
vitality  of  the  pulp.  This  is  the  principal  reason  why  we  find  so 
many  dead  pulps  under  such  fillings.  It  is  always  safer  to  remove 
the  decay  completely  and,  when  it  is  very  deep,  use  oxyphosphate 
of  zinc.  I  am  persuaded  that  much  of  the  bad  reputation  of 
oxyphosphate  of  zinc  as  a  pulp-capping  and  as  a  protection 
against  thermal  sensitiveness  in  deep  cavities  is  due  to  its  use 
over  a  more  or  less  thick  mass  of  carious  dentin,  and  especially 
over  pulps  already  infected  and  inflamed  from  undiscovered 
exposure  to  carious  dentin.  Pulps  thus  exposed  must  be  regarded 
as  inflamed  pulps  and  not  proper  subjects  for  capping.  Only 
those  pulps  that  become  exposed  in  the  removal  of  the  very  last 
particles  of  softened  material,  or  in  cutting  beyond,  are  suitable 
subjects  for  capping.  The  principal  use  for  oxyphosphate  of 
zinc  is  for  the  protection  of  pulps  nearly,  but  not  actually 
exposed.  In  deep  cavities,  the  actual  condition  is  not  discovered 
until  the  last  of  the  softened  dentin  is  removed.  Not  infrequently 
a  tooth  is  filled  when  the  pulp  is  fully  exposed  to  the  softened 
material;  death  of  the  pulp  follows  speedily.  Under  all  condi- 
tions every  particle  of  softened  material  should  be  removed,  and 
if  the  pulp  be  exposed  in  so  doing,  deal  intelligently  with  the  con- 
ditions found.  This  is  the  only  safe  line  of  treatment  in  any 
cavities  whatsoever. 

Pit  cavities  in  the  occlusal  surfaces  of  the  bicuspids  are  much 
less  frequent  than  in  the  molars,  and  when  there  has  been  rea- 
sonable watchfulness,  they  may  be  filled  when  small.  They  are 
therefore  easy  of  management.  They  begin  to  occur  at  from 
fourteen  to  sixteen.  These,  especially,  should  be  filled  early, 
for,  if  neglected,  the  burrowing  of  decay  is  pretty  certain  to 
undermine  the  marginal  ridge  and  a  portion  of  the  enamel  of 
the  proximal  surface.  By  this  extension  the  simple  pit  cavity  is 
converted  into  the  more  complicate  occluso-proximal  cavity, 
which  greatly  increases  the  difficulty  of  treatment.  For  this 
reason  one  should  be  especially  watchful  of  the  pits  in  bicuspids 
in  the  children  of  very  susceptible  families  and  fill  them  upon  the 
first  appearance  of  softening.  This  watchfulness  is  especially 
necessary  in  these  teeth  for  the  reason  that  the  pits  are  gen- 
erally small  and  the  beginnings  of  decay  very  much  hidden  until 


MANAGEMENT    OF    CAVITIES    BY    CLASSES.  207 

considerable  burrowing  has  occurred.  Careful  examination  of 
the  loroximal  surfaces  of  these  teeth  for  decay  should  always  be 
made  before  filling  these  pits  to  see  whether  or  not  they  may  need 
treatment.  The  proximal  surfaces  decay  much  more  frequently 
than  the  pits,  and  in  the  treatment  of  these,  the  pit  fillings  pre- 
viously made  must  always  be  removed  in  cutting  occlusal  anchor- 
ages. 

When  examining  for  pit  and  fissure  cavities  in  children  of 
families  highly  susceptible  to  caries,  tl;e  least  showing  of  the 
beginning  of  caries  should  not  be  allowed  to  pass  without  imme- 
diate treatment.  These  decays  are  too  often  allowed  to  burrow 
deeply  before  treatment  is  instituted.  The  dentist  should  never 
lose  sight  of  the  fact  that  in  young  persons  the  pulps  of  the  teeth 
are  much  larger  and  their  horns  are  much  longer  than  in  the 
teeth  of  mature  persons.  For  this  reason  the  pulp  becomes 
endangered  by  a  decay  of  much  less  depth.  Sometimes  they 
will  even  reach  the  pulp  of  the  tooth  before  making  any  notice- 
able showing  upon  the  surface.  The  carious  material  is  white, 
the  surface  of  the  enamel  is  complete  except  the  pit  or  fissure. 
It  may  show  through  the  enamel  as  a  grayish  area,  or  the  decay 
may  not  be  detected  except  by  the  fine-pointed  explorer.  All 
such  decays  occurring  in  susceptible  children  demand  immediate 
attention. 

After  writing  the  above  statement,  a  dentist  of  high  repute 
told  me  of  a  case  in  which,  in  examining  the  teeth  of  a  girl  about 
eighteen  years  old,  he  was  trying  the  pits  as  usual  with  the 
exploring  tine,  when,  to  his  surprise,  the  whole  enamel  cap  of 
a  bicuspid  came  away  with  the  instrument.  He  found  the  whole 
of  the  dentin  of  the  crown  a  softened  mass.  The  appearance  of 
the  tooth  had  given  no  suspicion  of  the  actual  condition. 

This  condition  must  be  differentiated  sharply  from  the  con- 
ditions so  often  found  in  older  persons,  in  which  these  pits  and 
fissures  are  much  darkened  or  actually  black.  This  dark  color 
occurs  where  some  slight  softening  of  the  enamel  has  taken  place 
earlier,  and  is  often  mistaken  for  active  decay.  It  is  rather  an 
evidence  of  immunity  from  the  beginning  of  new  areas  of  decay. 
But  there  may  be  an  active  area  of  decay  beneath  this  dark  col- 
oring, and  this  must  be  determined  by  the  explorer.  While  the 
dark  color  is  evidence  of  conditions  unfavorable  to  decay,  decay 
having  begun  may  be  continuing.  This  demands  examination, 
and  the  operator  will  be  controlled  by  the  conditions  found. 
Very  many  pits  show  evidence  of  some  slight  softening  in  early 
youth,  which  is  stopped  by  the  coming  of  immunity  or  some 


208  PATHOLOGY    OF    THE    HABD    TISSUES   OF    THE    TEETH. 

change  of  local  conditions.  Then  these  become  dark  in  color  and 
so  remain  without  further  change.  These  should  not  be  inter- 
fered with,  as  they  are  just  as  safe  without  any  filling  whatever. 

Cavities  of  the  Second,  Third  and  Fourth  Classes. 

These  include  all  cavities  in  the  proximal  surfaces  of  the 
teeth.  Although  properly  divided  into  three  classes  from  the 
standpoint  of  differences  in  technical  procedures,  the  second 
including  the  proximal  cavities  in  the  bicuspids  and  molars,  the 
third  including  the  ordinary  cavities  in  the  incisors  and  cuspids, 
and  the  fourth  those  in  which  an  angle  of  the  tooth  is  involved, 
the  conditions  from  the  standpoint  of  the  management  of  cases 
may  in  part  be  presented  together.  The  fourth  class  includes 
only  cavities  of  the  third,  in  which  extension  of  decay  has 
involved  the  angle  of  an  incisor  and  calls  only  for  differences  in 
the  technical  procedures.  It  may  therefore  be  eliminated  from 
present  consideration.  Decays  of  the  proximal  surfaces  are  the 
most  destructive  decays  that  occur  in  the  teeth  and  occupy  more 
of  the  dentist's  time  than  any  other.  They  also  call  for  a 
greater  degree  of  acuteness  and  skill  in  the  management  of  con- 
ditions than  any  other. 

In  the  order  of  occurrence,  these  cavities  follow  or  occur 
later  than  those  in  pits  and  fissures,  but  are  usually  earlier  than 
those  occurring  in  buccal  and  labial  surfaces.  It  must  be  under- 
stood, however,  that  this  expresses  the  general  rule  found  by 
making  averages  from  many  recorded  cases  and  to  which  there 
are  many  exceptions.  Between  the  time  and  the  frequency  of 
the  appearance  of  proximal  cavities  in  the  incisors  and  in  the 
bicuspids  and  molars,  there  is  the  utmost  variation  in  different 
individuals.  In  some,  the  incisors  will  escape  entirely  or  with 
but  one  or  two  cavities,  while  the  back  teeth  will  have  many; 
and  in  others,  the  case  will  be  reversed.  In  the  aggregate,  the 
liability  is  about  equal,  though  where  individual  proximal  sur- 
faces are  considered,  the  mesial  surfaces  of  the  central  incisors 
are  found  decayed  oftener  than  any  others.  The  broad,  flat 
mesial  surfaces  of  the  first  molars  stand  next  in  the  frequency 
of  decay.  In  any  of  the  teeth,  except  the  first  bicuspid,  the  mesial 
surfaces  are  oftener  decayed  than  the  distal  surfaces,  appar- 
ently because  they  are  less  rounded  in  contour.  In  considering 
these,  it  must  be  remembered  that  there  are  two  areas  of  liability 
—  one  mesial  and  one  distal  on  each  tooth  —  while  in  the  first 
and  fifth  classes  there  is  but  one,  except  as  buccal  pits  in  some  of 
the  molars  furnish  a  second.     Therefore,  if  the  liability  were 


MANAGEMENT   OF   CAVITIES   BY   CLASSES.  209 

equal,  the  proximal  cavities?  would  be  double  the  number  of 
either  the  first  or  fifth  classes. 

These  are  all  smooth  surface  cavities  —  that  is,  they  occur 
in  surfaces  on  which  the  enamel  of  the  tooth  is  perfect  and 
smooth,  presenting  neither  fissures,  pits  nor  grooves,  which  serve 
as  starting  points  for  decay.  The  conditions  are  therefore  rad- 
ically different  from  those  presented  in  pit  and  fissure  cavities. 
The  beginning  of  decay  in  these  smooth  surfaces  is  not  confined 
to  a  single  minute  point  in  the  enamel,  as  when  beginning  in  pits 
and  fissures,  but  the  surface  of  the  enamel  is  attacked  and  the 
area  will  be  great  or  small,  coinciding  with  the  size  of  the  local 
areas  of  uncleanness.  The  close  examination  of  a  large  number 
of  cases  shows  that  the  size  and  form  of  these  areas  depend 
mainly  upon  the  forms  of  the  proximal  surfaces,  and  the  amount 
and  form  of  those  parts  which  closely  approach  each  other. 
When  the  surfaces  are  well  rounded,  the  contact  points  small 
and  the  embrasures  wide  an'd  deep,  decay  is  less  apt  to  occur  and 
its  beginning  is  confined  to  a  narrower  area  of  surface,  or  often 
to  a  small  point ;  while,  if  the  proximal  surfaces  are  flat,  the  con- 
tacts broad  and  the  embrasures  shallow,  decay  is  more  liable  to 
occur  and  the  area  of  enamel  surface  attacked  will  be  propor- 
tionately broad.  Other  things  being  equal,  this  matter  of  forms 
of  the  surfaces,  their  contact  points  and  the  depth  of  the  embra- 
sures control  the  degree  of  cleanliness  of  these  surfaces  and  their 
liability  to  decay.  This  will  be  better  understood  by  reviewing 
Figures  86  to  95  inclusive,  illustrating  these  forms,  together 
with  the  text  relating  to  them.  All  of  this  will  be  modified  by 
the  degree  of  susceptibility  to  decay  and  by  personal  artificial 
cleaning.  The  susceptibility  of  the  person  will  constantly  be  the 
principal  factor,  modified  and  controlled  to  some  extent  by  the 
conditions  above  detailed.  At  the  present  time,  we  are  unable  in 
any  direct  way  to  control  this  principal  factor  —  susceptibility. 
In  prophylactic  treatment  our  attention  must  be  directed  to  the 
removal,  modification  or  improvement  of  those  local  conditions 
giving  opportunity  for  its  manifestations. 

The  key  to  the  rules  of  management  of  these  classes  of  cases 
is  found  by  noting  these  local  conditions,  and  in  the  study  of  the 
influences  they  exert  for  limiting,  increasing  or  modifying  the 
opportunities  for  the  beginning  and  superficial  spreading  of 
caries  of  the  enamel. 

The  forms  of  the  areas  of  liability  to  decay  are  different  in 
the  molars  and  lucuspirls  from  the  forms  presented  in  the  incisors 
and  cuspids,  because  of  the  differences  in  the  contour  of  proximal 


210  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE   TEETH. 

surfaces  of  these  teeth,  but  the  essential  characters  of  the  areas 
are  the  same  in  all,  so  that  they  are  really  much  alike.  The  con- 
ditions which  give  opportunity  for  these  decays  are  to  the  gingi- 
val of  the  contact  point. 

The  proximal  area  of  liability  to  decay  is  bounded  to  the 
occlusal,  or  incisal,  by  the  proximal  contact  point,  to  the  buccal, 
or  labial,  and  lingual  by  the  opening  of  the  embrasures  to  the 
excursions  of  food  during  mastication,  and  to  the  gingival  by  the 
position  of  the  margin  of  the  healthy  gum  septum. 

In  a  strict  account  of  the  examination  of  ten  thousand  per- 
sons who  applied  for  treatment  in  the  clinic  in  Northwestern 
University  Dental  School,  only  nine  persons  were  found  in  whose 
teeth  superficial  spreading  of  decay  of  the  enamel  had  passed 
across  the  angles  of  the  teeth  from  one  surface  to  another,  or 
had  extended  from  two  surfaces  and  met  across  the  angles.  All 
of  these  were  cases  of  imusual  severity  of  caries  that  had  been 
neglected  until  all  effort  to  chew  food  had  been  practically  aban- 
doned by  the  patients.  This  marks  the  angles  of  the  teeth,  or  an 
approach  to  them,  as  the  line  of  safety  along  which  to  lay  cavity 
margins  in  the  preparation  of  cavities  in  proximal  or  buccal 
surfaces.  It  also  points  out  that  the  angle  of  the  tooth  should 
not  be  passed  in  the  extension  of  cavities  imless  some  special 
condition  presents,  such  as  the  extension  of  caries  in  dentin, 
requiring  it. 

The  best  management  of  these  cavities  requires  that  the 
operator  make  a  study  of  each  individual  proximal  surface 
involved,  determine  the  boundaries  of  its  area  of  liability  to 
decay,  and  that  in  the  preparation  of  the  cavity,  the  whole  of  the 
area  of  liability  be  included  within  the  cavity  outline,  together 
with  such  area  of  the  occlusal  surface  in  bicuspids  and  molars 
as  may  be  necessary  to  give  convenience  in  operating  and  stabil- 
ity to  the  filling.  If  present  decay  only  be  removed,  the  cavity 
lines  not  being  extended  as  described,  decay  will  recur  about 
the  margins  of  the  filling,  causing  failure.  The  provisions  for 
maintaining  the  health  of  the  giun  septum  should  not  be  over- 
looked. Caries  never  makes  a  beginning  on  a  portion  of  the 
tooth  surface  covered  by  a  healthy  gum  septum  or  free  gum 
margin.  All  such  portions  are  strictly  immune.  A  margin  of  a 
filling  so  laid  that  it  will  be  continuously  protected  by  healtliy 
gum  tissue  is  as  safe  as  if  laid  upon  a  surface  fully  exposed  to 
the  friction  of  mastication.  Tlierefore,  the  preservation  of  the 
health  of  the  septum  of  gum  which  normally  fills  the  interproxi- 
mal space  to  the  contact  point  is  one  of  the  important  factors  in 


MANAGEMENT    OF    CAVITIES    BY    CLASSES.  211 

treatment.  It  follows,  that  in  the  preparation  of  these  cavities, 
they  must,  in  order  to  be  curative  and  prophylactic,  be  cut  so 
far  into  the  embrasures,  both  to  the  buccal  and  to  the  lingual, 
that  the  excursions  of  food  in  the  act  of  mastication  will  sweep 
their  marginal  lines  and  keep  them  constantly  cleaned,  and  the 
gingival  margin  must  be  so  laid  that  it  will  be  covered  by  the  gum 
septum.  Then,  if  the  form  of  the  proximal  surface,  and  espe- 
cially of  the  contact  point,  is  so  made  that  it  will  protect  this  gum 
septum,  and  is  sufficiently  prominent  to  preserve  the  full  mesio- 
distal  breadth  of  the  tooth,  the  permanence  of  the  filling  made 
with  technical  skill  is  assured.  The  cutting  of  cavities  to  these 
lines  is  termed,  extension  for  prevention.  It  applies  to  all  proxi- 
mal cavities. 

In  this  connection,  a  very  common  misconception  occurs  with 
the  observation  that,  in  many  cases  met  with  in  practice,  spread- 
ing of  decay  on  the  surface  of  the  enamel  has  gone  no  farther 
than  the  margin  of  the  open  cavity;  therefore  it  is  not  necessary 
to  extend  farther.  This  is  often  a  serious  error.  If,  in  the  prog- 
ress of  caries  of  the  enamel,  the  enamel  rods  fall  away  in  the 
central  portion  before  decay  has  spread  to  the  buccal  or  lingual 
as  far  as  opportimity  would  allow,  the  colony  of  microorganisms 
will  usuallj^  become  detached  and  not  grow  again  on  the  surface 
while  the  cavity  remains  open.  This  seems  to  be  because  of  the 
changed  conditions  caused  by  the  loss  of  the  central  nidus  of 
attachment.  When  a  filling  has  been  made  and  properly  formed, 
this  central  nidus  of  attachment  is  restored  and  growth  again 
occurs  on  the  filling.  The  filling  material  being  indestructible, 
this  growth  spreads  to  the  full  extent  of  opportunity  to  the  buccal 
and  to  the  lingual  and  will  overstep  the  boundaries  of  the  filling, 
causing  recurrence  of  decay.  Therefore,  if  safe  fillings  are  to  be 
made,  the  laying  of  the  boundaries  of  every  cavity  prepared 
should  be  determined  by  a  study  of  the  area  of  opportunity  for 
the  beginning  of  caries  rather  than  by  the  breadth  of  the  present 
decay.  The  boundary  of  opportunity  of  spreading  decay  toward 
the  buccal  or  lingual  will  be  determined  by  the  depth  of  the 
embrasures  and  consequent  breadth  of  near  approach  of  sur- 
faces, which  make  the  opportunity  for  cleaning  by  the  sweep  of 
food  through  them  in  mastication,  or  by  the  brush  in  artificial 
cleaning. 

The  study  of  recurring  caries  in  its  earlier  stages,  as  it  is 
presented  in  practice,  is  one  of  the  best  methods  of  informing 
oneself  of  the  conditions  causing  it.  For  this  to  be  most  valuable, 
those  cases  in  which  the  enamel  has  become  whitened  but  in 


212  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

which  no  enamel  rods  have  yet  fallen  out,  serve  the  best  purpose ; 
for  in  these  the  whole  condition  remains  unchanged.  After  actual 
cavities  have  been  formed,  it  is  often  difficult  to  be  certain 
whether  the  case  is  one  of  extension  of  decay  on  the  enamel,  or 
a  case  of  leakage  from  poor  adaptation  of  the  filling  material, 
or  the  faulty  preparation  of  an  enamel  margin.  If  these  early 
beginnings  of  recurrence  of  caries  are  noted  carefully  with  a 
studj^  of  the  nearness  of  the  approach  of  the  surface  of  the  proxi- 
mating  tooth  to  them,  the  opportunity  for  cleaning  of  the  cavity 
margin  by  excursions  of  food,  the  shapes  of  the  occluding  sur- 
faces as  controlling  food  pressure  through  them,  the  actual  con- 
ditions of  cleanliness  of  the  part,  together  with  the  habits  of  the 
patient  in  artificial  cleaning,  much  will  be  learned  of  the  condi- 
tions of  recurrence  of  decay  that  will  give  valuable  information 
for  guidance  in  the  management  of  this  class  of  cases.  These  are 
conditions  which,  I  am  persuaded,  very  few  dentists  have  learned 
to  stud}'  in  a  really  practical  way  that  will  make  the  information 
gained  available  in  practice.  "While  these  studies,  coupled  with 
a  proper  and  available  development  of  technical  skill,  ought  to 
place  the  dentist  in  such  rapport  with  his  cases  that  few  recur- 
rences of  decay  will  be  found  in  after  years,  it  is  too  much  to 
expect  that  these  will  be  actually  banished.  This  occurred  to  me 
some  time  ago.  In  1875  I  undertook  the  care  of  the  teeth  of  a 
young  man,  then  nineteen  years  old,  who  had  many  proximal 
cavities,  and  gingival  third  cavities  in  the  central  and  lateral 
incisors,  with  some  whitened  areas  on  the  gingival  thirds  of  the 
buccal  surfaces  of  the  bicuspids.  Altogether  it  seemed  an  ugly 
case.  After  a  study  of  it,  he  was  placed  under  pretty  close 
instructions  for  prophylactic  use  of  the  brush  and  made  com- 
fortable by  the  removal  of  two  exposed  pulps,  so  that  he  could 
make  full  use  of  his  teeth  again  and  recover  from  sensitiveness 
of  the  peridental  membranes  so  as  to  endure  the  mallet  well. 
The  fillings  were  made  without  hurry,  occupying  about  six 
months'  time.  The  extensions  were  full  and  free  as  I  could  now 
recommend.  "Within  the  next  four  years  several  other  decays 
were  found  beginning,  after  which  there  was  complete  immunity. 
In  1903  he  came  to  me  for  advice.  No  fillings  had  been  lost.  In 
several  cases  recent  recurrence  had  formed  cavities  at  the  bucco- 
gingival  angles  of  fillings.  "Wliitened  areas  of  beginning  decay 
were  demonstrable  in  a  similar  relation  to  every  proximal  filling 
and  every  gingival  third  filling  that  had  been  made.  Many  new 
decays  were  starting  in  areas  not  decayed  before.  Films  of  very 
firm  gelatinous  material  (plaques)  were  present  upon  all  of  the 


MANAGEMENT   OF   CAVITIES   BY   CLASSES.  213 

fillings  on  buccal  surfaces  or  other  positions  of  easy  access  for 
examination.  These  had  spread  beyond  the  margins  of  the  fill- 
ings. The  enamel  was  decaying  under  these  extensions.  Indeed, 
the  whole  denture  was  going  to  pieces  with  so-called  "chalky 
decay."  The  man  seemed  to  be  in  ordinary  health,  but  he  had 
had  a  reverse  in  fortune  a  few  years  before,  which  had  left  him 
despondent  and  he  had  become  entirely  careless  in  his  habits  of 
cleanliness.  His  teeth,  gums  and  peridental  membranes  had 
become  sensitive  (there  was  no  calculus)  and  he  had  almost 
ceased  to  chew  food.  The  only  chance  for  this  man  lay  in  a  com- 
plete change  to  cleanly  habits,  with  radical  training  in  the  masti- 
cation of  food.  Otherwise  fillings  would  be  of  little  value.  No 
amount  of  extension  for  prevention  would  have  been  available 
for  the  prevention  of  extension  of  decay  in  such  a  case  and  the 
effort  to  meet  such  conditions  in  that  way  should  never  be  made. 
Cases  of  lesser  gravity  will  occasionally  occur  in  practice  which 
can  not  be  covered  with  any  reasonable  extensions  of  cavity  walls. 
A  judicious  operator  will  make  no  effort  to  provide  for  such 
cases  in  his  general  plans  of  management  of  his  cases.  He 
should,  however,  so  manage  in  his  treatment  of  proximal  and 
gingival  third  cavities  that  such  recurrent  decay  will  not  be 
found  so  long  as  persons  are  making  reasonably  vigorous  use  of 
their  teeth  in  chewing  food.  During  the  past  year  I  was  con- 
sulted by  a  person  who  had  unusually  broad  whitened  areas  on 
all  of  the  buccal  and  labial  gingival  thirds  of  his  teeth,  and  much 
of  the  same  conditions  showing  in  the  proximal  surfaces.  From 
the  history  of  his  case,  it  appeared  that  he  had  recently  had 
typhoid  fever,  during  which  his  mouth  and  lips  were  much 
gummed  over  with  gelatinous  material  (sordes).  Except  for 
this,  he  had  been  immune  to  decay.  To  all  appearances,  he  was 
again  immune.  No  enamel  rods  had  fallen  out;  no  penetration 
of  enamel  had  yet  occurred;  the  teeth  were  disfigured  by  the 
change  in  color,  but  the  probability  is  that  further  decay  will 
not  occur.  The  whitened  areas  will  probably  become  dark  very 
slowly  if  the  strict  cleanliness  and  the  habit  of  vigorous  use 
of  the  teeth,  as  rebegim  after  his  recovery,  is  maintained.  Such 
beginnings  of  decay  following  typhoid  fever,  in  which  there 
has  been  much  sordes,  are  not  very  uncommon,  but  such  a  case 
as  above  related  is  very  rare.  It  serves  well  to  point  out  the 
usefulness  of  vigorous  mastication  of  food,  and  reasonable  and 
intelligent  use  of  the  brush  as  matters  of  treatment. 

These  processes,  taken  as  a  whole,  are  carried  out  for  their 
curative  and  prophylactic  value.    Many  persons  seem  to  think 


214  PATHOLOGY    OF    THE    HAED    TISSUES   OF    THE   TEETH. 

that,  in  the  matter  of  extensions  of  cavities,  simpler  fillings,  in 
the  technical  sense,  may  be  made,  and  have  been  made  success- 
fully in  these  cavities  in  the  past.  While  this  may  be  true  of 
some,  too  many  have  failed.  Experience  in  cutting  and  filling 
cavities,  according  to  the  rules  given  in  technical  procedures 
in  filling  teeth,  will,  by  comparison  of  results,  show  such  sup- 
posed simpler  cavities  to  be  lacking  in  prophylactic  value.  Decay 
is  continually  recurring  about  the  margins  of  the  fillings  when- 
ever they  are  involved  in  habitual  uncleanliness  of  even  moderate 
degree,  and  they  are  soon  undermined  and  destroyed.  For  this, 
extension  for  prevention,  intelligently  adapted  to  the  conditions 
and  skillfully  carried  out,  has  been  found  an  effective  remedy. 

LIMITATION    OP    EXTENSION    FOR   PREVENTION. 

In  the  use  of  extension  for  prevention,  there  is  no  call  for 
extension  aroimd  the  angles  of  the  teeth  onto  either  buccal,  labial 
or  lingual  surfaces.  Objection  has  been  made  in  some  journal 
articles  and  society  discussions,  that  cavities  had  to  be  cut  inordi- 
nately large  in  order  to  comply  with  the  requirements,  especially 
in  the  front  teeth.  This  is  from  a  misunderstanding  of  what  is 
meant.  In  the  front  teeth,  there  should  be  no  cutting  over  onto 
the  labial  surface,  nor  should  there  be  any  considerable  show 
of  gold  fillings  for  the  purpose  of  satisfying  the  rules  of  exten- 
sion for  prevention.  Decay  seldom  begins  on  the  angles  of  any 
of  the  teeth,  and  especially  is  this  rare  in  the  angles  of  the 
incisors  and  cuspids.  When  cavities  in  these  teeth  are  so  cut 
that  the  margins  approach  the  angles  sufiiciently  to  free  them 
well  from  near  contact  with  the  proximating  teeth,  extension 
for  prevention  is  satisfied.  An  approach  to  the  angle  on  that 
part  of  the  surface  rounding  up  to  it  is  what  is  called  for.  Any 
cutting  beyond  the  angle  is  in  direct  opposition  to  extension  for 
prevention,  because  it  is  then  approaching  an  area  of  surface 
that  is  less  safe.  In  the  preparation  of  a  cavity  in  an  incisor 
it  should  never  be  cut  over  onto  the  labial  surface  for  the  pur- 
pose of  extension  for  prevention.  It  is  only  when  decay  has 
extended  along  the  dento-enamel  junction  so  as  to  undermine 
and  practically  destroy  a  portion  of  the  enamel  of  the  labial 
surface  that  it  should  be  cut  away.  In  these  teeth,  the  necessities 
for  extension  for  prevention  relate  almost  exclusively  to  broad- 
ening the  cavity  to  the  labio-gingival  and  linguo-gingival  angles 
of  the  proximal  surface,  or  squaring  out  the  ordinary  rounded 
form  of  the  gingival  wall  and  making  the  labial  and  lingual 
walls  straight  from  near  the  incisal  angle  to  the  labio-gingival 


MANAGEMENT    OF    CAVITIES    BY    CLASSES.  215 

and  Hnguo-gingival  angles.  This  is  distinctly  pointed  out  and 
illustrated  in  the  volume  devoted  to  technical  procedures  in 
filling  teeth.  The  same  rules  apply  to  bicuspids  and  molars, 
with  this  difference:  Incisor  cavities  must  be  filled  from  the 
labial  or  lingual,  because  they  are  not  cut  out  to  the  incisal. 
Proximal  cavities  in  bicuspids  and  molars  are  cut  out  to  the 
occlusal  and  are  filled  from  the  occlusal  direction.  For  con- 
venience in  operating,  and  in  order  that  the  filling  can  with 
certainty  be  well  made,  it  is  necessary  that  the  cavity  be  as 
broad  bucco-lingually  at  the  occlusal  as  at  the  gingival  portion. 
Therefore,  any  extension  made  at  the  gingival  portion  toward 
the  buccal  or  lingual  must  be  carried  out  to  the  occlusal.  This 
makes  cavities  somewhat  larger  in  these  surfaces.  But  in  no 
case  is  it  necessary  in  satisfying  the  demands  of  extension  for 
prevention,  to  extend  fully  to  the  angle  of  the  tooth,  much  less 
beyond  the  angle.  Extension  for  prevention  has  no  relation 
whatever  to  the  depth  of  cavities.  Every  cavity  prepared  for 
filling  should  be  as  shallow  as  the  removal  of  all  carious  material 
will  allow  wherever  this  will  give  safe  anchorage  in  dentin.  This 
should  be  taken  as  the  expression  of  a  principle  in  all  treatment 
of  caries  by  filling.  Large  fillings  extending  far  out  onto  buccal 
or  labial  surfaces  should  be  made  only  when  demanded  by  actual 
extension  of  decay. 

In  highly  susceptible  persons,  proximal  cavities  are  very 
destructive  to  the  teeth  and  destroy  them  quickly.  In  such  cases, 
they  are  more  liable  to  attack  the  teeth  in  the  order  of  their 
eruption,  and  are  often  discovered  within  two  to  four  years  after 
the  teeth  have  taken  their  places  in  the  arch.  These  are  the 
most  difficult  of  cavities  to  treat  successfully.  "We  have  the 
child  to  deal  with,  the  teeth  become  abnormally  sensitive,  every 
movement  in  the  treatment  is  painful,  the  self-control  and  endur- 
ance of  the  patient  are  low,  and,  yet,  this  is  just  the  case  in 
which  prophylactic  cleaning  and  the  technical  procedures  in 
treatment  need  to  be  carried  out  with  the  greatest  degree  of 
minuteness  to  be  successful. 

For  a  number  of  years  the  fillings  must  resist  the  sharpest 
susceptibility  to  recurrence  of  decay.  The  operator  may  know 
well  his  duty  and  be  skillful  in  manipulation,  and  yet,  if  he  has 
not  the  moral  courage  back  of  his  convictions,  great  patience 
and  persistence,  he  will  do  well  to  transfer  the  little  patient  to 
some  one  better  qualified  in  these  particulars.  Even  with  the 
most  intense  susceptibility  some  of  the  proximal  surfaces  usually 
escape  decay,  the  local  conditions  as  to  form  and  cleanliness 


216  PATHOLOGY   OF    THE    HARD    TISSUES   OF    THE    TEETH. 

being  especially  favorable.  Often  the  proximal  surfaces  of  the 
front  teeth  will  decay  very  early,  and  those  of  the  back  teeth 
not  until  later,  or  not  at  all.  In  other  cases,  the  front  teeth 
escape  and  the  proximal  surfaces  of  the  bicuspids  and  molars 
decay  very  early.  In  either  ease  the  decays  are  very  apt  to 
occur  in  pairs,  similarly  located  one  upon  either  side  of  the 
mouth. 

A  mesial  cavity  occurs  occasionally  in  the  first  permanent 
molar  while  it  is  in  contact  with  the  second  deciduous  molar 
and  it  requires  treatment  very  early.  This  is  presented  fully 
under  the  heading  "Management  of  Children's  Teeth,"  and  need 
not  be  considered  further  here. 

This  is  the  only  proximal  cavity  in  the  molars  that  begins 
at  a  very  tender  age.  The  second  molar  is  not  erupted  until 
twelve,  and  rarely  has  a  cavity  before  fourteen  or  fifteen  in  the 
most  susceptible  children.  And  it  is  only  at  this  age  that  distal 
cavities  in  first  molars  begin  to  occur.  At  this  age,  however, 
we  may  expect  cavities  in  the  distal  surfaces  of  the  first  molars 
and  mesial  surfaces  of  the  second,  and  cavities  are  liable  to 
occur  in  the  proximal  surfaces  of  the  bicuspids  almost  as  rapidly 
as  they  take  their  places.  When  this  occurs,  the  teeth  melt  away 
with  great  rapidity  and  the  most  heroic  and  painstaking  operat- 
ing in  respect  to  minute  details  and  the  full  inclusion  of  areas 
of  liability  will  be  required  to  protect  them  until  the  coming  of 
immunity  relieves  them  of  danger.  All  tinkering  with  tem- 
porary fillings  should  be  avoided  to  the  utmost,  and  j'et  cases 
will  occur  in  which  temporary  fillings  must  be  resorted  to,  to 
bridge  over  periods  of  extreme  sensitiveness.  But  the  time  of 
their  use  should  be  confined  to  the  shortest  possible  limit.  At 
this  age,  the  failure  of  effective  use  of  the  teeth  in  chewing  food 
quickly  brings  with  it  sensitiveness  and  thickening  of  the  peri- 
dental membranes,  and  it  is  of  the  utmost  importance  to  have 
the  patient  using  the  teeth  vigorously  again  in  order  that  fillings 
may  be  made  without  inflicting  unbearable  pain,  and  also  on 
account  of  the  necessity  for  the  greatest  possible  cleanliness. 
Often  temporary  fillings  made  with  this  special  end  in  view, 
together  with  the  arousing  of  the  proper  effort  on  the  part  of 
the  patient,  will  accomplish  the  desired  end  quickly,  or  within 
a  month  or  two,  and  then  the  case  may  be  regarded  as  under 
control  and  the  necessary  fillings  leisurely  and  effectively  made. 
Many  dentists  push  their  young  patients  too  strongly.  That  is, 
they  make  their  sittings  too  frequent  and  too  long.  When  the 
patient  is  suffering  pain,  extreme  sensitiveness,  or  failing  in 


MANAGEMENT    OP    CAVITIES   BY    CLASSES.  217 

mastication,  it  is  better  to  make  the  sittings  short  and  frequent 
until  comfort  is  restored  and  conditions  obtained  which  permit 
of  effective  mastication.  Then  put  the  patient  to  vigorous  work 
with  the  teeth,  if  possible,  upon  extra  tough  or  hard  foods, 
giving  them  vigorous  exercise  three  times  per  day.  When  this 
has  been  continued  for  a  few  weeks,  the  sensitiveness  will  be 
so  diminished  that  effective  operating  may  be  done  without  great 
pain.  Sufficient  time  should  be  given  between  sittings  —  a  week 
or  more  —  to  allow  the  hyperesthesia  aroused  by  the  one  opera- 
tion to  pass  away  before  beginning  the  next.  In  this  way  the 
operations  may  be  continued  to  a  finish  with  a  continuous 
improvement  of  conditions.  Definite  plans  of  management  with 
these  ends  in  view  are  of  the  utmost  importance  in  extreme  cases 
of  hyperesthesia  with  notable  impairment  of  mastication.  Cases 
that  come  to  us  before  there  is  considerable  impairment  of 
masticating  power  are  more  easily  dealt  with,  and  permanent 
fillings  may  generally  be  made  at  once. 

Hyperesthesia  of  the  dentin  does  not  limit  the  use  of  the 
teeth  except  when  food  is  forced  into  the  cavity  in  such  a  way 
as  to  affect  the  dentin  directly.  Cases  of  extreme  hyperesthesia 
of  the  dentin  will  be  met  with  in  many  cavities  in  persons  who 
have  no  impairment  of  mastication.  Therefore,  in  these  cases, 
a  solid  filling,  one  that  does  not  move  or  shift,  cures  the  diffi- 
culty in  mastication  as  soon  as  the  patient  gains  confidence  that 
the  use  of  the  tooth  will  not  hurt.  This,  of  course,  relates  to 
cases  in  which  the  sensitiveness  has  occurred  so  recently  that 
there  has  been  no  impairment  of  the  tone  of  the  peridental  mem- 
branes, a  thing  which  often  occurs  when  the  occlusal  wall  of  a 
proximal  cavity  has  suddenly  broken  away,  exposing  the  cavity 
to  direct  food  pressure.  There  is,  in  such  cases,  no  reason  for 
deferring  the  final  filling  because  of  pain  in  malleting,  for  that 
will  be  borne  without  difficulty.  The  difficulty  is  only  in  the 
preparation  of  the  cavity.  But  the  question  of  thermal  sensi- 
tiveness and  the  danger  of  hy|:)eremia  of  the  pulp  will  require 
consideration.  In  a  large  proportion  of  the  cases  of  hypersensi- 
tive dentin  there  will  be  no  especial  thermal  sensitiveness.  This 
question  generally  relates  to  individual  teeth  and  does  not  mate- 
rially affect  the  treatment  of  other  cavities.  These  may  be 
proceeded  with  to  completion  without  delay,  or,  in  the  mean- 
time, the  sensitive  teeth  with  temporary  stoppings  will  have  so 
improved  that  the  extension  of  the  cavity  may  be  completed  and 
these  also  may  be  permanently  filled. 

Older  patients,  of  twenty  to  thirty-five  years,  often  present 


218  PATHOLOGY    OF    THE    HAED    TISSUES   OF    THE    TEETH. 

with  a  number  of  slowly  progressive  proximal  cavities  in  the 
bicuspids  and  molars,  or  cavities  in  which  fillings  have  failed. 
If  these  cases  are  not  so  bad  as  to  have  materially  limited 
mastication,  or  if  the  patient  has  not  contracted  mincing  habits 
at  table,  they  are  generally  easy  to  manage.  They  require  little 
else  than  the  careful  performance  of  the  required  technical  pro- 
cedures after  a  study  of  the  requirements  of  extension  for  pre- 
vention in  the  individual  cavities. 

If,  however,  the  case  presents  many  open  cavities  that  have 
long  rendered  chewing  painful  and  ineffective,  and  the  habit  of 
avoiding  foods  requiring  effort  in  mastication  has  been  long  con- 
firmed, they  may  prove  exceedingly  difficult  to  treat.  The  whole 
mouth  is  often  in  a  condition  of  hyperesthesia;  everything  we 
do  for  them  hurts.  In  operating  we  must  treat  them  as  we 
would  treat  children,  but  otherwise  as  adults.  Often  we  must 
gain  their  confidence  by  selecting  the  least  painful  operations 
in  the  beginning,  and  then,  as  rapidly  as  possible,  remove  the 
hindrances  to  mastication  and  train  them  into  the  vigorous  use 
of  their  teeth.  It  is  often  well  to  use  temporary  fillings  in  those 
cases  requiring  long,  tedious  packing  of  gold  until  chewing  has 
become  effective  and  the  membranes  strong  and  firm.  Then  the 
necessary  malleting  to  make  a  good  filling  can  be  borne  without 
difficulty. 

If,  in  any  such  cases,  there  are  pulp  exposures  that  are 
preventing  the  patient  from  chewing  food,  these  must  be  elimi- 
nated by  the  appropriate  treatment  as  a  first  procedure  whenever 
practicable.  Operators  most  often  overlook  bad  contacts  or 
ojien  cavities,  which  allow  food  to  so  impinge  upon  the  gums  as 
to  continually  cause  pain.  Whenever  such  places  are  present, 
they  should  be  treated  with  temporary  fillings  in  such  a  way  as 
to  substantially  remove  the  difficulty  without  waiting  for  the 
more  tedious  permanent  operations.  The  recovery  of  the  health 
of  the  gums,  and  particularly  of  the  gum  septums,  and  recovery 
of  the  peridental  membranes  from  sensitiveness  caused  by  irri- 
tation and  lack  of  use,  should  always  be  especially  looked  to  in 
the  making  of  temporary  fillings,  and  these  must  be  so  made  as 
to  promote  this.  Often  gutta-percha  is  forced  upon  the  gum 
septum  in  such  a  way  as  to  cause  its  absorption  and  do  per- 
manent injury.  This  should,  by  all  means,  be  guarded  against 
with  jealous  care;  for,  when  it  occurs,  the  interproximal  space 
will  be  continuously  unclean,  except  as  it  is  cleaned  artificially. 
This  becomes  a  continuous  menace  to  the  health  of  the  parts. 
When  this  has  occurred,  every  effort  should  be  made  by  artificial 


MANAGEMENT    OF    CAVITIES    BY    CLASSES.  219 

cleaning  and  the  mild  stimulation  of  the  interproximal  gum 
tissue  to  induce  a  regrowtli  that  will  fill  the  space.  This  will 
often  be  successful,  but  often  it  will  fail. 

Thermal,  sensitiveness  is  met  with  more  frequently  in  the 
management  of  cavities  in  the  upper  incisors  than  any  other 
teeth,  apparently  for  the  reason  that  they  are  most  exposed  to 
cold  air.  Precautions  against  this  should  be  taken  wherever 
possible.  The  conditions  make  the  use  of  oxyphosphate  of  zinc 
or  other  non-conducting  material  under  these  fillings  more  diffi- 
cult than  in  other  teeth.  The  cavities,  even  when  deep  for  the 
locality,  are  still  so  broad  compared  with  their  depth,  and  the 
requirements  for  anchorage  are  so  imperative,  that  there  seems 
to  be  no  room  for  the  oxyphosphate  of  zinc.  In  most  cases, 
when  it  is  demanded,  the  operator  may  contrive  to  overcome  the 
technical  difficulties,  or  he  may  substitute  a  bit  of  quill,  which 
is  just  as  effective  as  a  non-conductor,  and  does  not  occupy 
appreciable  space.  Careful  instruction  to  patients  regarding 
the  danger  of  thermal  sensitiveness  and  the  means  at  their 
command  of  avoiding  it,  is,  after  all,  the  most  effective  protec- 
tion. Instruction  in  the  use  of  the  quill  as  a  non-conductor  will 
be  found  in  technical  procedures  in  filling  teeth. 

In  bicuspids  and  molars,  the  form  of  the  occlusal  surface, 
in  its  relation  to  the  interproximal  space  and  the  embrasures, 
is  occasionally  of  great  importance  to  the  cleanliness  of  the  parts. 
In  the  normal  occlusion,  the  arrangement  of  the  teeth  is  such 
that  the  cusps  of  an  upper  molar  or  bicuspid  are  in  position 
to  force  the  food  into  and  through  the  embrasures,  buccal  and 
lingual,  of  the  lower  teeth.  The  cusps  of  the  lower  teeth  are  in 
position  to  perform  the  same  service  for  the  upper;  that  is, 
a  portion  of  the  occlusal  surface  of  the  teeth  of  the  one  jaw  over- 
hangs the  embrasures  of  the  other,  and,  in  every  act  of  chewing, 
the  food  is  forced  to  sweep  through  these  embrasures. 

This  forms  the  natural  method  of  cleaning  them,  as  has 
been  related  in  the  text  in  relation  to  Figures  101,  102,  103. 
Irregularities  of  the  teeth  often  prevent  this  form  of  cleaning 
being  effectively  done.  Also  the  forms  of  teeth  may  be  such 
in  particular  instances  that  it  is  not  well  done.  In  many  eases 
where  a  more  effective  cleaning  of  an  interproximal  space  by  the 
process  of  mastication  seems  desirable,  the  form  of  the  part  of 
the  occlusal  surface  formed  by  the  filling  may  be  so  modified 
that,  in  the  crushing  of  food,  a  greater  amouut  of  it  will  be 
directed  into  the  embrasure  and  effect  a  more  thorough  cleaning 
of  the  marginal  lines  of  a  filling.    This  may  usually  be  done  by 


220  PATHOLOGY    OF    THE    HAED    TISSUES   OF    THE    TEETH. 

cutting  away  some  portion  of  the  marginal  ridge  and  so  sloping 
the  surface  toward  the  embrasure  that,  when  the  food  is  crushed 
upon  it,  it  will  tend  to  slide  into  and  through  the  embrasure. 

A  change  in  the  form  of  the  proximal  surface  may  often 
be  made  that  will  improve  the  cleaning  of  the  parts,  especially 
in  broad  proximal  cavities  in  the  molars  and  bicuspids.  The 
distal  surface  of  the  first  molar,  particularly  when  the  disto- 
lingual  cusp  is  large  and  protrudes  to  the  distal  so  that  the 
lingual  embrasure  is  much  narrowed,  will  not  have  its  disto- 
lingual  angle  well  cleaned  by  the  excursions  of  food,  and  on  this 
account  decay  is  especially  liable  to  occur  along  the  gingival  por- 
tion of  the  lingual  margin  after  the  filling  is  made,  if  the  original 
form  is  preserved  or  reproduced.  In  this  case  it  is  much  better 
to  carry  the  cutting  somewhat  beyond  the  disto-lingual  angle  of 
the  tooth,  and,  in  finishing  the  filling,  reduce  the  distal  protru- 
sion of  this  cusp  and  widen  the  embrasure.  If,  at  the  same  time, 
the  distal  marginal  ridge  is  left  low,  or  the  occlusal  surface 
sloped  a  little  toward  the  embrasure,  so  as  to  direct  the  crush 
of  food  into  it,  the  cleaning  of  the  lingual  margin  of  the  filling 
will  be  so  improved  as  to  prevent  this  tendency  to  recurrence 
of  decay  at  this  point. 

In  the  bicuspids  there  are  great  differences  among  differ- 
ent individuals  in  the  mesio-distal  breadth  of  the  lingual  cusps 
as  compared  with  the  buccal.  Wlien  the  lingual  cusps  are  broad 
in  this  direction,  the  lingual  embrasures  are  very  narrow,  so 
that  the  cleaning  of  the  lingnial  marginal  lines  of  fillings  will 
be  very  imperfect;  these  embrasures  should  be  broadened  by 
narrowing  the  lingual  cusps  wherever  practicable,  or  by  separat- 
ing the  teeth  sufficiently  to  build  out  a  prominent  contact  point, 
and  the  occlusal  surface  so  finished  as  to  direct  the  excursions 
of  food  into  and  through  these  embrasui'es  so  that  they  will  be 
continually  cleaned  by  the  act  of  mastication.  In  making  these 
form  changes,  every  care  must  be  had  to  slightly  increase  the 
mesio-distal  breadth  of  the  tooth  at  the  contact  point.  The 
observant  operator  will  find  many  places  other  than  those  cited 
in  which  to  apply  the  principles  which  the  particular  cases  given 
illustrate.  Wlienever  cases  of  great  intensity  of  susceptibility 
to  decay  demand  treatment,  eveiy  means  at  our  command  of 
increasing  or  facilitating  the  natural  cleaning  of  the  marginal 
lines  of  our  fillings  should  be  studied  for  the  individual  case. 

LODGMENTS   OF    FOOD    IN    TTTK    INTEBPKOXIMAL    SPACE. 

The  effect  of  lodgments  of  food  in  the  interproximal  space 
has  been  pointed  out  in  connection  with  the  two  groups  of  illus- 


MANAGEMENT    OF    CAVITIES    BY    CLASSES.  221 

trations,  Figures  121-123  and  124-128,  inclusive.  Good  manage- 
ment of  cases  requires  especial  watchfulness  for  such  conditions. 
No  case  in  which  lodgment  is  suspected,  or  in  which  complaint 
is  made  by  a  patient,  should  be  allowed  to  pass  without  the 
closest  scrutiny  and  a  determination  of  the  facts.  Often  there 
will  be  no  complaint  by  the  patient  on  which  to  base  a  special 
examination,  and  sometimes  the  symptoms  remain  very  obscure 
until  much  injury  has  been  done.  This  insidiousness  of  the  con- 
ditions is  one  of  its  greatest  dangers.  In  many  of  the  cases, 
however,  in  the  absence  of  complaint  by  the  patient,  the  symp- 
toms are  plainly  marked.  The  most  prominent  symptoms  are 
the  swelling  and  redness  of  the  interproximal  gum  tissue,  and  an 
enlargement  of  its  festoons  on  the  buccal  or  lingual,  or  both,  in 
some  one  or  more  of  the  interproximal  spaces,  without  apparent 
reason  to  be  seen  in  the  general  conditions  of  the  mouth.  This 
may  be  so  prominent  that  it  will  catch  the  eye  of  a  skilled 
observer  at  once,  or  it  may  be  so  slight  as  to  easily  escape  notice. 
In  many  of  the  cases  in  which  increased  redness  is  not  apparent, 
the  gum  tissue  will  have  become  festooned,  i.  e.,  the  tissue, 
instead  of  rounding  smoothly  into  the  interproximal  space  as  is 
normal  in  healthy  mouths,  becomes  enlarged  and  pointed  in 
the  embrasure.  This  may  occur  as  a  general  condition  of  the 
gums  in  cases  of  a  slight  gingivitus  from  nncleanness,  or  occa- 
sionally, from  constitutional  causes.  The  condition  passes  away 
readily  when  the  causes  which  induced  it  have  been  removed. 
This  general  condition  must  not  be  confused  with  the  local  con- 
dition occurring  at  isolated  points.  "When  patients  complain 
of  pain  from  forcing  food  into  any  interproximal  space,  a  care- 
ful examination  will  generally  show  that  the  central  portion 
bucco-lingually  of  the  gum  septum  has  been  absorbed  by  the 
pressure  of  the  retained  food,  forming  a  pocket  of  more  or  less 
depth.  "Wlien  the  patient  has  not  complained  but  still  the  symp- 
toms noted  above  are  found,  careful  examination  will,  usually, 
reveal  similar  conditions.  This  will  confirm  the  diagnosis  in 
either  case.  Then  it  becomes  necessary  to  determine  the  cause 
of  the  condition  and  to  remedy  it.  In  many  cases  it  will  be  found 
to  be  caused  by  the  roughening  of  the  proximal  surfaces  by 
beginning  decay  and  the  remedy  is  in  making  the  appropriate 
filling,  or  fillings,  in  proper  form.  This  should  not  be  delayed 
because  the  decay  is  as  yet  very  slight.  Figures  121-123  show 
conclusively  that  wide  extensions  of  decay  toward  the  gingival 
occur  from  this  cause,  making  a  grave  complication  of  the  case 
even  before  the  enamel  rods  have  fallen  away  in  the  original 


222  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE   TEETH. 

beginning  point  of  decay  of  the  enamel.  This  is  sufficient  evi- 
dence that  delays  foi'  any  considerable  time  are  dangerous. 

In  other  cases  the  difficulty  may  be  caused  by  a  cavity  that 
has  become  larger  and  possibly  partially  open  to  the  occlusal 
surface.  In  any  siich,  the  duty  of  the  operator  is  too  clear  to 
be  questioned.  The  same  is  true  if  the  cause  be  found  in  contacts 
much  flattened  by  wear,  as  in  Figures  124-128,  inclusive.  A 
few  cases  in  which  none  of  these  conditions  are  present  may  give 
trouble  in  the  determination  of  the  cause,  but  generally  a  close 
investigation  will  determine  it. 

When  decay  has  extended  far  to  the  gingival  from  this 
cause  and  is  still  conf5ned  to  the  enamel,  as  shown  in  Figures 
121-123,  it  will  not  appear  in  the  excavation  of  the  cavity,  if 
firmness  of  the  tissue  of  the  gingival  wall  to  cutting  instru- 
ments is  relied  upon  as  a  guide.  Often  the  existence  of  a  pocket 
between  the  teeth  will  lead  one  to  suspect  it.  The  examination 
must  finally  be  made  by  the  eye  in  a  good  light,  the  cavity  being 
dry.  If  there  is  an  extension  of  decay  to  the  gingival  because 
of  lodgments  of  debris,  it  will  appear  as  a  light,  chalky  line  on 
the  cavo-surface  angle  of  the  gingival  wall.  Then,  of  course, 
the  cutting  must  be  continued  until  this  is  removed. 

Finally,  good  management  of  cases  demands  that  fillings 
in  proximal  surfaces  be  so  formed  that  lodgments  of  food  in  the 
interproximal  spaces  shall  not  occur.  Otherwise,  all  of  the  evils 
related  above  will  occur  after  the  filling  is  made  and  it  will  be 
lost  by  recurring  decay  at  the  gingival  margin  of  the  filling.  This 
is  fully  discussed  from  the  technical  standpoint  in  the  second 
volume. 

PROPHYLACTIC   VALUE    OF   FORM   IN    PROXIMAL   FILLINGS. 

The  form  given  to  proximal  surface  fillings  is  of  the  utmost 
importance  in  the  prevention  of  recurrence  of  decay,  and  in 
the  prevention  of  the  occurrence  of  disease  of  the  gums  and  peri- 
dental membranes.  The  points  to  be  attained  are:  (1)  The 
preservation  of  the  full  mesio-distal  breadth  of  the  tooth  crown; 
(2)  correct  form  of  proximal  surface;  (3)  correct  form  of  inter- 
proximal contact;  (4)  the  health  of  the  gum  septum.  The 
general  rule  will  be  that  the  original  form  of  the  teeth  should 
be  reproduced  in  the  filling,  but  it  often  happens  that  the  orig- 
inal form  is  not  the  best  form,  and  in  such  cases,  when  practi- 
cable, the  form  should  be  improved.  The  most  essential  features 
are  that  the  contact  point  be  well  roundcnl  so  that  it  will  touch 
the  proximating  tooth  only  at  a  small  rounded  point,  and  that 
this  be  sufficiently  i^rominent  to  restore  the  original  tooth  form 


MANAGEMENT    OF    CAVITIES    BY    CLASSES.  223 

and  therefore  restore  the  full  normal  breadth  of  the  interprox- 
imal space.  This  requires  that  the  teeth  be  separated  sufficiently 
to  allow  the  finish  to  be  made  without  in  any  degree  narrowing 
the  mesio-distal  breadth.  Indeed,  it  is  better  to  widen  this  just 
a  little.  Careful  measurements  show  that  when  the  average 
person  has  arrived  at  the  age  of  forty  years,  he  has  lost,  by 
wear  of  the  proximal  contacts  of  his  teeth,  one  centimeter  in 
length  of  the  arch  measured  around  the  labial  and  buccal  sur- 
faces of  the  teeth  from  the  mesial  cusp  of  the  right  third  molar 
to  the  mesial  cusp  of  the  left  third  molar.  Some  of  this  loss 
should  be  restored  with  every  proximal  surface  that  it  is  neces- 
sary to  fill.  When  the  forms  of  the  teeth  have  been  good,  their 
restoration  reinstates  the  normal  conditions,  and  cleanliness 
and  health  are  readily  maintained. 

If,  on  the  other  hand,  the  mesio-distal  breadth  is  not 
restored,  the  two  teeth  will  soon  be  crowded  together,  narrowing 
the  interproximal  space,  and  the  crowding  upon  the  gum  septum 
will  cause  its  partial  absorption.  It  will  be  shortened  and  will 
fail  to  fill  the  narrowed  interproximal  space,  affording  oppor- 
tunity for  lodgments  in  a  position  difficult  to  clean.  The  embra- 
sures are  also  narrowed  by  reason  of  the  teeth  falling  together, 
which  prevents  the  excursions  of  food  through  them  in  masti- 
cation, and  increases  the  area  of  liability,  or  carries  its  borders 
farther  toward  the  angles  of  the  teeth,  so  as  to  place  the  mar- 
gins of  the  filling  in  greater  danger  of  recurrence  of  decay. 

When  the  proximal  contact  is  not  sufficiently  prominent 
to  restore  the  mesio-distal  breadth  of  the  tooth,  it  is  necessarily 
flattened  and  broadened,  and  is  in  that  degree  less  well  adapted 
to  maintain  the  cleanliness  of  the  space.  If  it  is  flattened  to 
any  considerable  degree,  it  will  not  only  fail  to  be  self -cleaning, 
but  will  grasp  and  hold  stringy  particles  of  food.  These  will 
be  forced  upon  the  gum  septum,  causing  pain  in  mastication, 
which  will  be  a  grave  annoyance.  Absorption  of  the  gum  septum 
will  occur,  forming  a  pocket  that  will  hold  debris,  which  will 
decompose  and  cause  recurrence  of  decay  at  the  gingival  mar- 
gin of  the  filling,  or  it  will  cause  disease  of  the  peridental  mem- 
brane, with  final  loss  of  the  tooth.  It  will  also  endanger  the 
neighboring  teeth.  The  failure  to  obtain  correct  forms  of  inter- 
proximal surfaces  caused  widespread  loss  of  fillings  from  recur- 
rence of  decay  at  the  gingival  border,  when  dentists  first  began 
making  contour  fillings  with  cohesive  gold. 

In  practice,  cases  are  frequently  presented  of  teeth  that 
have  been  neglected,  in  which  the  contact  points  have  been  lost 


224  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE   TEETH. 

from  caries,  and  the  teeth  have  crowded  together,  closing  up  the 
normal  interproximal  space  until  the  necks  of  the  teeth  have 
come  close  together.  If  these  are  filled  ever  so  well,  without 
separation  and  moving  the  teeth  apart  sufficiently  to  restore 
their  original  form  and  the  original  breadth  of  the  interprox- 
imal space,  the  proximal  contact  will  necessarily  be  flat  and  will 
continue  to  hold  debris,  which  will  be  forced  upon  the  gum  and 
the  difficulty  will  not  be  improved.  The  remedy  is  in  the  restora- 
tion of  a  normal  form  by  restoring  the  breadth  of  the  inter- 
proximal space  and  mesio-distal  breadth  of  the  teeth  with  the 
normal  form  of  the  contact  point. 

Cases  will  be  presented  frequently  in  which  numbers  of 
teeth  have  been  filled  without  making  this  restoration,  and  the 
patient  is  in  continual  trouble,  often  to  such  a  degree  that 
mastication  is  seriously  limited,  or  serious  conditions  in  the 
form  of  recurrence  of  decay  or  disease  of  the  peridental  mem- 
branes are  threatened.  In  these  cases  the  remedy  is  in  the 
restoration  of  the  normal  form  as  above  indicated  by  separating 
the  teeth  and  refilling. 

Many  cases  are  presented  in  which  the  proximal  contacts 
are  very  broad  and  flat,  and  the  embrasures  narrow  and  shallow. 
The  teeth  are  thick  at  their  necks  and  the  proximal  surfaces  very 
flat.  Wlien  cavities  have  occurred  in  the  proximal  surfaces  of 
such  teeth,  it  is  best  to  increase  the  mesio-distal  breadth  of 
the  teeth  as  much  as  possible  and  make  the  proximal  contacts 
more  prominent  than  they  originally  were.  This  will  increase 
the  breadth  of  the  interproximal  space  and  the  depth  of  the 
embrasures,  contribute  to  cleanliness,  give  greater  comfort  in 
mastication  and  reduce  the  liability  to  recurrence  of  decay.  In 
cases  in  which,  from  loss  of  contact,  by  reason  of  decay  or  by 
improper  previous  operations  involving  a  considerable  number 
of  the  teeth  in  the  arch,  considerable  time  should  be  allowed  for 
the  whole  restoration.  One  or  two  of  the  spaces  should  be 
restored,  and,  when  possible,  a  month  of  rest  should  be  given 
for  the  general  adjustment  of  the  arch  to  the  new  conditions. 
Then  one  or  two  more  spaces  should  be  widened,  and  so  con- 
tinue to  the  finish.  In  this  way  a  very  considerable  difference 
may  be  made  in  the  arch  without  special  difficulty. 

The  contact  points  between  the  teeth  become  flattened  by 
wear  one  upon  the  other,  so  that  frequently,  in  middle-aged  or 
elderly  people,  certain  of  them  become  so  much  flattened  that 
they  hold  stringy  foods  between  them.  Food  is  forced  upon 
the  gum  septum  in  every  effort  at  mastication,  causing  pain, 


MANAGEMENT    OF    CAVITIES    BY    CLASSES.  225 

absorption  of  the  gum  septum  and  disease  of  tlie  peridental 
membrane,  and,  in  many  cases,  decay  of  the  teeth  occurs,  begin- 
ning near  the  gingival  line.  These  decays  are  very  difficult  to 
treat.  See  Figures  124-128,  inclusive.  Whenever  these  are 
noticed,  their  treatment  should  be  undertaken  as  described  in 
the  second  volume. 

Cavities  of  the  Fifth  Class. 

Cavities  of  the  fifth  class  include  those  occurring  in  the 
buccal  and  lingual  surfaces  of  the  bicuspids  and  molars  —  not 
pit  cavities,  and  in  the  labial  surfaces  of  the  incisors  and  cuspids. 
They  are,  therefore,  all  smooth-surface  cavities.  They  are  infre- 
quent in  lingual  surfaces.  In  order  of  occurrence,  these  are 
usually  later  in  life  than  cavities  of  the  other  classes,  though  in 
this  the  greatest  variety  occurs.  Occasionally  they  occur  very 
early,  even  appearing  in  the  deciduous  teeth,  but  this  is  rare. 
Occasionally  they  occur  in  old  age.  In  this  case  they  are  often 
termed ' '  senile  decay. ' '  In  the  molars,  cavities  of  this  class  must 
be  sharply  distinguished  from  pit  cavities.  These  are  all  smooth 
surface  cavities  and  occur  in  the  smooth  portion  of  the  enamel 
to  the  gingival  of  the  pit,  generally  in  the  gingival  third  of  the 
surface  close  to  the  gum  margin.  They  are  somewhat  rare  before 
the  age  of  sixteen  or  eighteen,  and  are  oftener  seen  at  from  eight- 
een to  twenty-five.  When  they  begin  very  early,  they  are  diffi- 
cult cavities  to  treat.  They  are  not  only  difficult  in  themselves, 
but  are  coincident  with  cavities  of  the  other  classes,  marking 
very  intense  susceptibility  and  complicating  the  whole  case  at  an 
age  when  the  patient  is  difficult  to  control.  On  these  accounts,  it 
is  the  intention  to  give  the  general  principles  of  their  manage- 
ment very  fully  in  this  place,  repeating  much  of  that  which  has 
been  said  before  under  the  head  of  clinical  features. 

In  the  buccal  surfaces  of  the  bicuspids,  and  in  the  labial  sur- 
faces of  the  incisors,  there  are  no  pits  and  all  the  cavities  are 
of  this  class.  In  all  of  the  teeth,  including  the  molars,  these 
cavities  begin  close  to  the  gma  margin.  The  distance  from  the 
gingival  line  will  depend  upon  the  length  of  the  free  margin  of 
the  gum.  When  they  occur  early,  the  margin  of  the  gum  is 
long  and  the  beginning  is  some  distance  away  from  the  gingival 
line,  leaving  a  good  margin  of  enamel,  provided  the  cavities  have 
not  been  neglected  until  they  have  become  so  large  that  it  is 
undermined  by  decay  of  the  dentin.  Some,  in  which  the  decay 
of  the  enamel  is  slow,  will  be  placed  in  better  position  by  the 
further  protrusion  of  the  tooth,  or  the  shortening  of  the  free  gum 


226  PATHOLOGY    OF    THE    HAED    TISSUES    OF    THE    TEETH. 

margin,  and  decay  will  cease  before  penetration  of  the  enamel 
has  occurred.  Such  areas  will  become  brown  or  black  with  the 
coming  of  immimity  to  the  region,  and  remain  as  dark  spots  in 
the  enamel.  They  should  not  be  disturbed.  "When  they  begin 
late,  the  free  margin  of  the  gum  has  shortened  so  that  the  begin- 
ning is  very  close  to  the  gingival  line,  which  soon  becomes 
involved  if  neglected.  When  they  occur  late  in  life  —  at  from 
forty  to  sixty  —  they  most  frequently  begin  just  at  the  gingival 
line,  and  often,  where  there  has  been  some  recession  of  the  gums, 
they  begin  in  the  cementum.  In  old  age  they  usually  begin  in 
the  cementum.  It  follows,  therefore,  that  the  position  of  the  area 
of  liability  in  this  class  of  cavities  differs  considerably  at  differ- 
ent ages  of  the  patient,  being  well  removed  from  the  gingival  line 
toward  the  occlusal  in  the  young,  close  to  the  gingival  line  in  the 
adult,  and  includes  the  gingival  line  in  middle  life  and  old  age. 
At  all  ages,  however,  the  area  of  liability  is  limited  toward  the 
gingival  by  the  free  margin  of  healthy  gum  tissue;  toward  the 
occlusal  by  the  limit  of  habitual  uncleanliness  of  the  surface,  and 
toward  the  mesial  and  distal  by  the  margins  of  the  surface,  or 
the  angles  of  the  tooth.  In  the  most  highly  susceptible  persons, 
the  superficial  beginning  of  decay  may  pass  the  angles  of  the 
tooth  and  join  with  the  area  of  liability  of  the  proximal  surfaces. 
This  never  occurs  except  in  cases  of  unusual  neglect. 

The  first  appearance  of  decay  in  the  enamel  is  usually  in 
the  form  of  a  narrow  strip  of  whitening  and  softening  close  to, 
and  following,  the  curve  of  the  free  border  of  the  gum  margin, 
or  just  at  that  point  of  the  surface  that  is  least  perfectly  cleaned 
by  the  friction  of  mastication.  The  extent  of  the  area  of  begin- 
ning decay  will  correspond  with  the  area  of  uncleanliness  of  the 
surface.  Occasionally  this  is  quite  broad  occluso-gingivally,  but 
more  generally  it  is  narrow,  and  not  infrequently  it  is  reduced 
to  a  mere  line  less  than  a  millimeter  in  breadth.  Mesio-distally, 
or  along  the  border  of  the  gum,  this  line  varies  much  in  length, 
but  is  rarely  less  than  one-third  the  breadth  of  the  surface,  more 
often  occupies  two-thirds  the  breadth,  and  occasionally  extends 
from  the  mesial  to  the  distal  angle  of  the  tooth.  The  first  pene- 
tration of  the  enamel  is  usually  central  to  this  area,  but  not  infre- 
quently extended  in  a  line  of  minute  breaks,  which  unite,  as  they 
enlarge,  forming  an  elongated  cavity.  Unless  cavities  have 
gained  considerable  size  before  they  are  seen,  there  is  always  a 
streak  of  softened  enamel  running  away  from  the  cavity  to  the 
mesial  and  to  the  distal,  in  which  the  decay  has  not  yet  reached 
the  dentin. 


MANAGEMENT    OP    CAVITIES    BY    CLASSES.  227 

In  the  preparation  of  buccal  and  labial  cavities  for  filling, 
good  management  requires  that  all  of  the  area  of  uncleanliness 
be  removed  at  once,  including,  of  course,  the  last  traces  of  soft- 
ened enamel,  no  matter  how  sound  and  perfect  the  dentin  may 
be  beneath.  The  occlusal  line  of  the  cavity  margin  should  be 
placed  so  far  to  the  occlusal  that  it  will  be  kept  clean  by  masti- 
cation of  food,  the  gingival  line  should  be  placed  so  that  it  will  be 
well  covered  by  the  gum  margin,  and  the  mesial  and  distal  lines 
should  be  placed  at  the  most  favorable  points  near  the  mesial  and 
distal  angles  of  the  tooth.  The  object  is  the  removal  of  the  area  of 
liability  to  decay  for  the  prevention  of  its  recurrence.  Wherever 
the  susceptibility  to  this  class  of  decay  is  considerable,  nothing 
less  will  effect  a  cure.  If  in  these  cases  the  cavity  in  the  dentin, 
simply,  is  excavated  and  filled  ever  so  well,  decay  will  go  on  so 
qiiickly  to  the  mesial  and  to  the  distal  of  the  filling  that  it  will 
be  of  no  value.  Formerly  these  were  regarded  as  the  most  uncer- 
tain of  fillings,  because  of  this  speedy  recurrence  of  the  decay, 
but  since  the  principles  of  extension  for  prevention,  as  above 
detailed,  have  been  used  in  their  treatment,  these  fillings  have 
become  almost  as  certain  of  long  endurance  as  fillings  in  occlusal 
cavities.  The  main  point  in  their  successful  treatment  is  the 
careful  study  of  the  local  conditions,  the  condition  of  suscepti- 
bility being  appreciated,  and  so  cutting  the  cavity  as  to  meet 
these  conditions.  This  becomes  a  matter  of  judgment  in  each 
individual  case,  and  upon  this  judgment  success  or  failure 
depends.  It  is  always  safer  to  cut  wider  than  necessary  than  to 
faU  a  little  short. 

The  greatest  difficulties  are  met  with  when  these  decays 
occur  in  the  teeth  of  young  persons.  In  such  cases  the  teeth  are 
more  apt  to  be  hypersensitive  and  the  patient  difficult  to  control, 
and  great  patience,  persistence  and  moral  courage  are  required 
of  the  operator  to  enable  him  to  carry  the  cutting  to  the  proper 
limit.  At  the  same  time,  the  requirements  for  extension  of  the 
cavities  are  much  greater  than  in  older  persons.  The  suscepti- 
bility to  decay  is  greater.  More  time  must  elapse  before  there 
is  relief  by  the  coming  of  immunity,  and  for  these  reasons  more 
is  required  of  the  filling.  Also  the  free  margin  of  the  gum  is 
long  in  young  persons  and  becomes  shorter  as  age  advances,  and 
if  these  cavities  are  not  extended  well  to  the  gingival,  the  gingival 
margin  will  become  uncovered  and  exposed  later,  and  come  to 
occupy  the  central  area  of  liability  to  decay.  Under  such  con- 
ditions recurrence  of  decay  along  this  margin  is  certain  if  the 
susceptibility  continues  and  safe  cleanliness  is  not  maintained 


228  PATHOLOGY   OF   THE   HABD   TISSUES   OF   THE   TEETH. 

by  the  sufficient  use  of  the  brush.  This  can  be  done,  however, 
and  recurrence  of  decay  prevented  if  the  patient  is  sufficiently 
careful  in  the  cleaning. 

"VAHien  these  cavities  occur  in  numbers  in  the  teeth  of  young 
girls  or  young  married  women  complicated  with  many  proximal 
decays  that  interfere  with  chewing  food,  and  are  neglected,  the 
conditions  become  the  worst  that  are  met  with  in  dental  practice. 
These  seem  not  so  frequent  now  as  they  were  thirty  or  forty 
years  ago  for  the  reason,  apparently,  that  there  is  not  the  same 
neglect  of  them,  but  occasionally  such  cases  will  be  presented. 
On  account  of  several  exposed  pulps  in  occlusal  and  proximal 
cavities,  the  patient  becomes  unable  to  chew  food,  and  practically 
ceases  to  use  the  teeth.  What  food  she  takes  is  of  the  softest 
variety,  often  mostly  starchy  foods,  cleaning  by  mastication  fails, 
artificial  cleaning  is  entirely  neglected,  cavities  of  decay  are  filled 
with  fermentable  material,  hyperesthesia  is  greatly  increased, 
and  gingival  third  decays  become  general.  In  this  condition 
the  patient  is  harassed  day  and  night  with  pain,  becomes  anemic 
and  some  intercurrent  affection  is  liable  to  end  life,  when  under 
normal  oral  conditions,  recovery  would  have  been  easy  and  sure. 
Early  in  my  practice  a  number  of  these  cases  occurring  together 
with  this  result,  aroused  me  more  than  any  other  thing  that 
has  ever  engaged  my  attention.  For  some  years  afterward  I 
extracted  all  the  teeth  and  made  artificial  teeth,  sometimes  in 
persons  not  more  than  sixteen  to  eighteen  years  old.  As  years 
went  on,  I  found  these  persons  again  in  very  bad  condition  on 
account  of  the  great  shrinkage  of  the  alveolar  processes.  They 
were  again  placed  in  a  condition  in  which  they  could  not  chew 
food  with  any  degree  of  satisfaction  or  comfort.  The  result  has 
been  a  very  close  clinical  study  of  these  conditions  and  of  the 
treatment  possible  in  these  neglected  cases  in  young  people. 

The  first  thing  to  do  is  to  relieve  pain,  and  on  account  of 
the  extreme  sensitiveness  of  the  persons,  the  most  difficult  thing 
is  to  gain  that  control  of  them  that  will  give  opportunity  for  the 
necessary  manipulation.  Confidence  must  be  obtained  slowly. 
Artificial  cleaning  must  be  instituted,  and  gradually  each  sensi- 
tive point  that  interferes  with  it,  eliminated.  Exposed  pulps 
must  be  removed  and  the  cavities  filled  temporarily.  No  perma- 
nent fillings  whatever  should  be  attempted.  All  buccal  or  labial 
cavities  in  which  decay  is  burrowing  in  the  dentin,  should  be 
fully  opened  by  clipping  away  all  overhanging  enamel,  and  left 
as  wide  open  as  possible  in  order  to  admit  free  washing,  both  in 
artificial  cleaning  and  by  fresh  clean  saliva.    The  softened  mate- 


MANAGEMENT    OF    CAVITIES    BY    CLASSES.  229 

rial  in  these  should  be  removed  by  piecemeal,  as  it  can  be  done 
without  much  pain,  and  the  washing  continued  with  an  abundance 
of  tepid  water  used  with  the  brush  after  each  meal  and  before 
retiring  at  night.  With  the  buccal  and  labial  cavities  the  whole 
effort  for  some  time  should  be  directed  to  the  relief  of  acidity 
by  washings,  and  the  strictest  uncovering  of  all  decayed  areas,  so 
that  the  acid  being  formed  in  the  tissues  may  be  dissolved  and 
removed.  But  no  alkalies  should  be  used ;  these  have  continually 
done  harm. 

In  this  way  the  -sensitiveness  in  the  teeth  will  be  rapidly 
diminished.  By  careful  removal  of  all  hindrances  to  masti- 
cation and  encouragement  in  the  use  of  the  teeth,  the  chewing 
of  food  may  again  become  established.  When  this  has  been 
accomplished  the  operator  may  leisurely  make  the  permanent 
fillings  required. 

This  is  an  illustration  of  the  principles  of  management  that 
should  be  followed  in  many  cases  of  much  less  gravity  than  those 
related  above.  When  this  has  been  carefully  done,  and  good  con- 
ditions have  been  obtained  for  making  the  permanent  fillings, 
and  habits  of  artificial  cleaning  have  become  well  established,  it 
is  often  surprising  how  quickly  complete  inmiunity  to  caries  will 
occur.  But  the  dentist  must  not  hurry  the  permanent  fillings. 
For  this  he  must  wait  until  the  weakened  peridental  membranes 
have  regained  their  strength  and  tone.  No  man  is  able  to  do 
his  best  work  in  filling  teeth  over  tender  peridental  membranes. 
In  following  these  cases  with  the  gnathodynamometer,  patients 
have  increased  the  crushing  power  with  their  teeth  from  twenty- 
five  or  thirty  pounds  to  one  hundred  and  sixty  or  one  hundred 
and  seventy  pounds,  within  a  few  months.  With  this  recovery 
of  normal  conditions,  any  foods  may  be  masticated  with  pleasure, 
and  the  very  best  of  operating  may  be  done. 

When  these  cavities  occur  as  late  as  eighteen,  or  later,  and 
are  treated  promptly,  they  are  not  difficult  to  treat  successfully. 
When  good  judgment  is  used  and  the  technical  procedures  well 
carried  out,  good  results  are  very  certain  and  satisfactory.  The 
same  may  be  said  of  similar  cavities  occurring  in  middle  life. 
Those  beginning  in  the  cementum  in  old  age  (senile  decays)  are 
often  very  annoying,  and  present  much  difficulty.  The  softening 
often  includes  a  wide  area  that  is  so  situated  as  to  be  very  diffi- 
cult to  keep  dry.  Safe  cavity  walls  are  difficult  to  obtain,  and 
pulp  exposure  in  the  canals  of  the  roots,  particularly  of  the 
molars,  is  very  liable  to  complicate  the  cases.  Fortunately,  these 
cases  are  not  frequent,  but  when  they  do  occur,  they  require  a 


230  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE    TEETH. 

special  study  of  the  local  conditions  and  the  very  careful  appli- 
cation of  procedures  to  meet  them. 

Cavities  of  this  class  are,  in  the  aggregate,  much  less  fre- 
quent than  cavities  of  the  other  classes.  In  practice  the  author 
has  found  them  very  annoying  from  the  fact  that  they  have  so 
often  occurred  after  the  case  seemed  fully  under  control.  This 
has  been  especially  true  in  women.  Young  girls  quite  suscepti- 
ble to  caries  have  grown  up  to  maturity,  other  classes  of  decay 
having  been  kept  well  under  control.  They  have  married,  and, 
perhaps,  in  their  first  or  second  pregnancy,  a  half  dozen  buccal 
cavities  suddenly  appear  and  urgently  require  treatment  at  a 
time  that  is  anything  but  opportune,  and  are  therefore  especially 
liable  to  be  neglected.  The  circumstances  make  them  very  diffi- 
cult to  handle. 

Prophylactic  measures  against  this  class  of  cavities  can  be 
rendered  more  effective  than  in  any  other.  The  surfaces  are  so 
exposed  to  the  brush  that  they  can  be  perfectly  cleaned  most 
easily.  If  patients,  at  the  first  signs  of  the  coming  of  this  class 
of  decay,  can  be  induced  to  use  a  brush  effectively  four  times  a 
day,  after  meals  and  before  retiring  at  night,  regularly,  for  a  few 
years,  they  will  escape  with  only  the  cavities  already  begun.  To 
be  effective,  however,  the  brushing  must  be  done  thoroughly  and 
regularly.    Only  the  brush  with  water  is  needed. 

CAEIES   IN    CASES   OF   RECESSION   OF   THE   GUMS. 
ILLUSTRATIONa :    FIGURES  168171. 

Caries  occurring  in  the  cementum  in  cases  of  recession  of 
the  gums  on  the  labial  surfaces  of  one,  two  or  more  teeth  in 
mouths  otherwise  healthy,  is  not  very  uncommon.  They  are 
always  unsatisfactory  cases  with  which  to  deal.  It  appears  quite 
certain  that  the  recession  of  the  gum  gives  the  opportunity  for 
the  caries,  and  as  the  recession  of  the  gum  is  often  progressive, 
so  is  the  area  involved  in  caries  enlarged.  Many  cases  of  reces- 
sion of  the  gum  occur  without  caries  that,  to  all  appearance,  are 
of  precisely  similar  nature.  This  recession  of  gum  is  a  very 
singular  phenomenon.  Often  there  seems  to  be  no  pathological 
condition  present  and  thus  far  very  little  has  been  accomplished 
in  the  endeavor  to  limit  it,  much  less  to  cure  it  and  obtain  a 
regrowth  of  the  lost  tissue. 

But  in  this  place  we  are  interested  chiefly  in  the  manage- 
ment of  caries  that  is  liable  to  begin  in  the  cementum  uncovered 
by  the  recession  of  the  gum.    In  many  instances  this  is  a  broad, 


MANAGEMENT    OF    CAVITIES    BY    CLASSES.  231 

flat  decay  occupying  the  surface  of  cementmn  exposed,  some- 
times encroaching  upon  the  gingival  portion  of  the  enamel,  and, 
in  other  cases,  sharply  limited  by  the  gingival  line,  as  shown  in 
Figure  169.  Often  the  progress  is  slow.  In  a  very  considerable 
proportion  of  these  cases  presenting  for  treatment,  the  dentist 
has  the  oi:)portuuity  of  treating  them  before  much  penetration 
has  occurred,  though  in  others  the  penetration  of  the  dentin  is 
rapid,  forming  a  deep  and  dangerous  cavity.  In  this  latter  case, 
the  only  alternative  is  a  mechanical  repair  by  some  kind  of  fill- 
ing. The  choice  of  this  will  depend  much  upon  conditions  of 
exposure  to  view.  If  it  be  the  upper  incisors  or  cuspids  and  the 
lips  are  very  mobile  so  that  the  defect  is  brought  prominently 
into  view  in  the  ordinary  movements  in  conversation  and  laugh- 
ing, a  porcelain  inlay  would  seem  to  be  demanded.  This  may  be 
made  gum  color  and  conceal  the  recession  of  gum.  If,  however, 
the  conditions  are  such  that  the  defect  does  not  come  into  view, 
gold  may  be  used. 

Fillings  of  any  kind  in  this  position  have  been  unsatisfactory 
for  the  reason  that  in  a  considerable  proportion  of  cases  the 
recession  of  the  gum  continues  to  progress,  uncovering  more 
cementum,  and  decay  again  occurs  in  the  part  newly  uncovered. 
The  filling  fails  to  protect  against  recurrence  of  the  decay  and 
must  be  repeated  at  intervals  so  long  as  the  recession  continues. 
The  filling,  whether  it  be  gold  or  porcelain,  does  successfully 
limit  the  penetration,  however,  and  in  that  degree  is  successful. 
When  depth  of  penetration  demands  it,  filling  is  the  best  treat- 
ment and  the  only  treatment  now  known  that  promises  long  con- 
tinued usefulness  of  the  tooth. 

On  the  other  hand,  those  cases  that  are  seen  early,  before 
much  penetration  of  caries  has  occurred,  may  be  treated  with 
silver  nitrate  and  penetration  of  decay  prevented  for  many  years 
by  occasional  repetition  of  the  treatment.  From  the  esthetic 
point  of  view,  this  treatment  is  more  unsightly  than  the  gold  fill- 
ing, for  the  surface  decayed  becomes  jet  black.  Therefore,  its 
use  is  limited  to  those  conditions  and  positions  in  which  this  fea- 
ture is  not  a  very  serious  objection.  In  applying  this  treatment, 
the  rubber  dam  is  placed  and  the  Hatch  clamp  applied,  as  shown 
in  Figure  168,  so  as  to  give  perfect  command  of  the  situation. 
Then  the  decayed  area  is  cleaned  and  dried  but  is  not  excavated 
in  any  degree.  Instead,  the  decayed  area  is  to  be  filled  as  deeply 
as  possible  with  the  salts  of  silver  nitrate  precipitated  by  light. 
It  is  well  to  dry  the  softened  area  as  deeply  as  possible  with  the 
warm  air  blast.    Make  a  saturated  solution  of  silver  nitrate  by 


232  PATHOLOGY   OF   THE   HAED   TISSUES   OF   THE   TEETH. 

crushing  a  small  crystal  on  a  glass  slab  and  adding  a  single  drop 
of  water.  Apply  this  to  the  area  of  decay  with  a  thin  end  of  an 
orangewood  stick  and  saturate  the  entire  area  thoroughly.  If 
possible,  place  the  patient  in  the  direct  rays  of  the  sun  for  ten  or 
twenty  minutes.  In  that  time  an  intense  black  color  should  be 
obtained,  such  as  is  shown  in  Figures  169,  170,  171,  which  were 
photographed  directly  from  the  mouth  after  this  treatment  and 
have  had  no  retouching.  If  direct  sunlight  can  not  be  obtained, 
use  the  best  daylight  obtainable  and  continue  the  exposure  for  an 
hour  or  more.  Many  of  the  cases  treated  in  this  way  do  very 
well  indeed,  and  it  is  very  easy  to  follow  up  a  further  recession 
of  gum  by  a  repetition  of  the  treatment.  It  must  be  distinctly 
understood  that  the  silver  nitrate  without  the  precipitation  by 
light  is  valueless.  It  is  dissolved  out  and  disappears.  It  is  only 
the  insoluble  black  precipitate  that  is  effective  and  the  decayed 
tissue  should  be  filled  with  it  completely  and  to  the  greatest  depth 
possible. 

Esthetic  Considekations. 

There  would  seem  to  have  been  sufficient  consideration  else- 
where of  questions  of  esthetics  in  the  treatment  of  caries  of  the 
teeth  without  a  separate  mention  under  that  head.  Yet  there 
are  some  points  not  touched  upon,  or  perhaps  that  have  not  been 
made  sufficiently  clear. 

The  point  that  gives  offense  most  often  in  this  regard  in 
the  treatment  of  caries,  is  making  gold  fillings  that  are  so  large 
as  to  overlap  onto  the  labial  surfaces  of  the  incisor  teeth.  When 
this  occurs,  it  is  usually  made  necessary  by  the  burrowing  of 
decay,  and  the  injury  to  the  appearance  of  the  teeth  can  not  be 
remedied  by  the  ordinary  methods  of  operating.  Porcelain  inlays 
may  be  used  in  these  cases,  but  their  use  in  young  people,  in 
whose  teeth  the  carious  process  is  still  active,  is  not,  as  yet, 
to  be  trusted  as  sufficiently  permanent  under  these  conditions. 
Therefore,  we  are  limited  to  making  the  best  appearance  possible 
under  the  conditions.  This  best  appearance  is  best  subserved 
by  making  the  necessary  show  of  gold  in  the  most  perfect  tooth 
form  possible.  A  mass  of  gold  appearing  in  an  incisor  that  has 
not  the  form  of  the  natural  surface  of  the  tooth  is  inexcusable. 
Such  a  presentation  adds  the  insult  of  bad  taste  in  operating  to 
the  injury  of  the  loss  of  the  part  of  the  tooth. 

On  the  other  hand,  if  the  building  of  the  filling  to  the  form 
of  the  tooth  has  been  artistically  done  in  all  of  its  details,  there 


Fig.    168.    The  rubber  tiain  and  the  Hatch  clamp  photographed  as  adjusted  in  a  case  of  caries  of 
the  labial  surface  of  the  riglit  lower  cusjiid  preparatory  to  treatment. 


«:. 


^ 


y 


r 


-7' 


Fio.   169.     A  case  of  recession  of  giini   with  superficial  cariee  of  the  uncovered  area  of  cemcntum 
after  treatment  with  silver  nitrate.     Piiotographed  directly  from   the  mouth. 


y  /if        ^ 


Fig.  170. 


Fig.  170.     Case  of  recession  of  gum  and  superficial  caries  of  the  uncovered  area  of  cementum  after 
treatment  with  silver  nitrate.     Photographed  directly  from  the  mouth. 


Fig.  171. 


Fig.    171.     Case  of   recession  of  gum  and  treatment    with   silver   nitrate. 
from  the  mouth. 


Photoeraphed    di  rectly 


MANAGEMENT    OF    CAVITIES    BY    CLASSES.  233 

will  be  a  beauty  in  the  expression  of  the  necessary  repair  -whicb 
does  much  to  amend  the  injury. 

In  many  of  these  cases  much  can  be  done  by  a  careful  limita- 
tion of  the  cutting  away  of  undermined  enamel  on  the  labial  sur- 
faces of  the  incisors  and  cuspids.  Esthetic  considerations  will 
often  justify  some  considerable  risk  of  future  fracture  of  weak- 
ened enamel  that  would  not  be  justifiable  in  any  other  position. 
But,  when  the  enamel  is  so  thin  and  so  transparent  that  the  yel- 
low color  of  gold  will  show  through  it,  the  result  will  be  worse 
than  to  cut  it  boldly  away  and  make  a  well-executed  restoration. 

One  of  the  constant  errors  in  filling  badly  decayed  incisor 
teeth  is  the  failure  to  restore  the  full  mesio-distal  breadth  of  the 
teeth  filled.  There  is  no  other  one  thing  that  mars  the  beauty 
of  a  face  more  than  building  a  gold  filling  in  one  central  incisor 
that  has  lost  its  contact  from  decay  and  dropped  against  its 
neighbor,  without  spreading  the  teeth  apart  so  as  to  restore  the 
full  mesio-distal  breadth  and  the  perfect  tooth  form.  Such  a 
restoration  made  with  a  porcelain  inlay  of  perfect  shade  and 
adaptation  otherwise,  would  still  be  a  serious  blemish.  A  perfect 
tooth  form  is  more  important  to  the  expression  of  the  general 
features  than  perfect  color.  Hence,  a  large  gold  filling  of  fine 
outline  and  finished  form  will  give  a  far  better  esthetic  effect 
than  the  finest  inlay  of  imperfect  form.  With  the  same  care, 
however,  and  the  same  tasteful  tact  in  the  restoration  of  form, 
the  inlay  may  be  made  as  perfect  in  this  respect  as  the  gold.  The 
point  in  either  case  is  the  attainment  of  perfect  contour  and  fin- 
ish. A  failure  in  this  will  remain  a  failure,  no  matter  what  the 
material  used  or  its  otherwise  perfect  adaptation. 

In  the  use  of  gold  in  the  front  teeth,  the  particular  direction 
of  the  reflection  of  light  from  the  filling  is  of  much  esthetic  impor- 
tance. Many  proximal  fillings  are  made  with  the  labial  margin 
so  placed  as  to  show  quite  plainly  and  yet  do  not  come  far  enough 
to  the  labial  to  reflect  light  to  the  observer,  and  for  that  reason 
appear  more  as  a  dark  cavity  than  as  a  filling.  When  the  extent 
of  decay  makes  it  necessary  to  cut  so  far  as  this,  these  will 
always  be  better  from  the  esthetic  standpoint  if  cut  a  little  far- 
ther toward  the  labial,  or  a  trifle  over  onto  the  labial  surface,  so 
that  their  true  character  will  be  plainly  apparent.  That  is,  the 
appearance  of  a  large,  well-formed  gold  filling  is  much  better 
than  a  small  filling  that  gives  the  appearance  of  a  dark  cavity. 
The  same  rule  as  to  perfect  form,  comparative  size,  and  position 
as  to  reflection  of  light,  applies  in  the  restoration  of  lost  parts  of 
all  teeth  that  come  into  view,  no  matter  where  they  are  situated 


234  PATHOLOGY   OF   THE   HAED   TISSUES   OF   THE   TEETH. 

or  what  material  may  be  used  in  the  restoration.  Hence  it  applies 
to  artificial  crowns  and  to  artificial  teeth  on  plates  as  well  as  to 
the  restoration  of  parts  of  crowns  in  filling  operations. 

The  marring  of  the  beauty  of  the  form  of  the  teeth  by  wear 
is  of  frequent  occurrence  in  middle  age  or  later,  and  occasionally 
in  younger  persons.  In  these  cases,  imperfect  occlusion  has 
caused  the  incisal  edges  of  the  front  teeth  to  be  shortened  irregu- 
larly. For  instance,  the  mesial  angles  of  the  central  incisors  may 
have  worn  much  more  than  the  distal  angles,  giving  the  teeth 
a  particularly  unsightly  appearance.  Generally,  this  appearance 
may  be  much  improved  by  so  grinding  the  teeth,  that  to  appear- 
ance, the  wear  will  be  regular.  This  may  often  be  done  to 
advantage  even  when  it  is  necessary  to  shorten  several  other 
teeth  in  order  to  regain  a  neat  and  pleasant  expression  of  the 
mouth.  Many  other  forms  of  irregular  wear  will  be  presented 
in  a  general  practice,  in  which  good  taste  will  prompt  a  similar 
correction.  Any  such  work  must  be  directed  by  good  taste  and 
judgment  to  obtain  good  esthetic  effects.  The  conditions  requir- 
ing this  kind  of  interference  vary  so  greatly  that  nothing  more 
than  this  very  general  statement  can  be  given. 


MANAGEMENT    OF    CHILDREN'S    TEETH.  235 


MANAGEMENT   OF    CHILDREN'S    TEETH. 

ILLUSTRATIONS:    FIGURES  172-186. 

The  conditions  calling  for  differences  in  the  treatment  of 
caries  in  children's  teeth  and  the  management  of  cases  in  them, 
in  comparison  with  adults,  are  due  to  childhood  purely.  Caries 
in  children's  teeth  is  not  different  from  caries  ha  the  teeth  of 
adults.  An  inflamed  tooth  pulp  or  an  alveolar  abscess  is  the 
same  in  its  nature  in  the  deciduous  tooth  of  the  child  as  in  the 
permanent  tooth  of  the  adult.  So  far  as  the  tissues  of  the  teeth 
are  concerned,  we  may  make  fillings  in  children's  teeth  just  the 
same  as  we  make  fillings  in  the  adult's  teeth.  The  tissues  of 
the  teeth  are  hard  enough ;  they  are  strong  enough.  The  differ- 
ences we  must  make  in  operating  do  not  lie  in  the  tissues  of  the 
teeth,  but  are  differences  due  to  childhood.  We  are  handling 
immature  persons,  whose  nervous  systems,  power  of  reasoning 
and  of  self-control  are  not  yet  developed,  and  we  have  all  of  the 
difficulties  that  belong  to  this  period  of  life. 

The  child  is  a  bundle  of  impulses,  each  of  which  is  ready  to 
break  into  action  without  notice  or  restraint.  Much  too  fre- 
quently the  dentist's  first  meeting  with  the  child  is  when  it  has 
been  wrought  up  by  pain  imtil  its  nerve  endings  are  all  on  the 
alert  ready  to  take  fright  at  the  least  suggestion  of  further  suf- 
fering. 

Children  are  quick  to  discover  a  failure  to  perform  a  prom- 
ised service,  and  if  that  failure  has  resulted  in  pain  to  them  in  the 
attempted  operation,  or  if  the  suffering,  the  relief  of  which  was 
sought,  continues,  the  child-thought  is  that  it  has  been  injured  or 
deceived.  They  are  not  much  disposed  to  excuse  an  operator  for 
difficulties  their  own  actions,  or  their  resistance,  have  imposed. 
Their  resentment  is  quick  and  sharp,  and  usually  without  reserve 
or  concealment.  On  the  other  hand,  they  are  just  as  quick  to 
recognize  a  success.  A  child  who  has  been  tortured  by  pain  and 
has  rebelled  and  fought  against  a  painful  operation  for  its  relief, 
will,  after  finding  the  promised  relief  and  comfort,  have  a  warm 
smile  of  confidence  for  the  person  who  conferred  the  benefit  and 
readily  forget  the  pain  inflicted.  Such  is  the  nature  of  the  child. 
Children  act  from  impulse  rather  than  by  processes  of  reasoning. 
Touch  them  right  and  they  are  easy  of  control;  when  touched 
wrong,  they  flash  like  powder.  The  important  questions  in  deal- 
ing with  the  diseases  of  children's  teeth  that  differ  from  dealing 


236  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE   TEETH. 

with  similar  conditions  in  adults,  is  in  obtaining  that  control  of 
the  child  nature  that  -will  give  opportunity  to  do  for  them  that 
which  is  best;  or  to  continue  expedients  that  will  succeed  tem- 
porarily until  increasing  age  and  greater  self-control  will  give 
better  opportunity. 

But  this  should  be  said :  Never  break  dovra  the  courage  of 
a  child  by  any  operation ;  never  break  down  the  nervous  system 
of  a  child ;  never  give  a  child  a  nervous  shock  that  it  will  recover 
from  tardily;  better  delay  an  operation,  better  do  almost  any- 
thing than  do  this.  It  is  true  that  in  some  cases  demanding  the 
extraction  of  a  tooth,  we  must  perform  the  operation,  cost  what 
it  will ;  we  must  relieve  the  patient  of  suffering ;  but  children 
bear  a  shock  of  this  kind  quite  well.  If  an  operation  that  is  very 
severe  is  over  in  a  few  moments,  giving  the  child  the  opportunity 
to  recover  at  once,  the  child  usually  will  recover  without  difiB- 
culty.  Tedious,  prolonged  operations,  those  that  come  day  after 
day,  break  down  a  child's  nervous  system  and  destroy  the  child's 
courage.  The  child  forgets  a  severe  hurt  quickly,  but  the  nervous 
shock  that  comes  from  continuous  and  repeated  operations  is 
that  which  breaks  down  the  child  most.  There  is  another  thought 
that  it  is  well  for  everyone  to  remember  —  to  succeed  with  a 
child  is  of  the  utmost  importance,  if  you  wish  to  retain  control 
of  the  child.  To  fail  of  success,  is  to  make  an  enemy  of  the  child. 
Therefore,  the  careful  planning  of  operations  for  them  is  of 
special  importance.  Children  do  not  forget  these  things  readily ; 
they  grow  up  with  an  impression  of  hatred  toward  this  or  that 
person  who  has  undertaken  to  make  operations  for  them  and  has 
failed.  On  the  other  hand,  if  you  succeed  and  gain  the  confidence 
of  the  child,  it  will  grow  up  your  friend  and  will  make  other 
friends  for  you.  These  are  very  important  considerations  in  the 
handling  of  children. 

In  the  handling  of  children  the  psychic  influences  are  of 
importance.  Some  persons  control  children  easily;  children 
take  to  them,  while  they  seem  to  shun  others ;  particularly  when 
it  comes  to  operations  that  are  painful,  children  fail  to  give  them 
their  confidence.  Often  persons  who  are  skillful  operators  and 
able  to  command  a  large  practice,  can  not  operate  well  for  chil- 
dren; children  do  not  like  them  for  some  reason.  Others  seem 
particularly  fitted  for  the  handling  of  children  in  their  distress ; 
they  control  children  easily.  There  is  something  in  the  approach 
that  gains  the  confidence  of  the  child.  This  can  be  cultivated  in 
a  large  degree.  Generally  those  persons  who  have  a  great  love 
for  children  control  them  well.    But  this  is  not  the  universal  rule. 


MANAGEMENT   OF   OHILDBEN'S   TEETH.  237 

The  vagaries  of  the  minds  of  children  are  very  difficult  to  under- 
stand. Often  they  will  give  their  confidence  to  a  stranger  when 
they  will  not  give  their  confidence,  so  far  as  painful  operations 
are  concerned,  to  persons  whom  they  know  well.  One  will  often 
do  well,  on  finding  that  he  has  failed  in  gaining  the  confidence  of 
a  child,  to  recommend  it  to  someone  else,  or  have  someone  else 
see  it  with  him.  Possibly  he  may  gain  the  little  fellow's  confi- 
dence in  that  way  and  retain  it  afterward.  This  will  often  make 
a  strong  favorable  impression  on  a  child  and  it  is  of  great  impor- 
tance in  the  management  of  a  practice.  "VVe  are  too  liable  to 
neglect  the  little  children ;  feel  that  operations  for  them  are  not 
of  much  consequence.  But  children  make  men,  and  their  friend- 
ship tells  in  after-practice.  One  will  often  have  to  do  that  for 
children  that  will  not  seem  to  pay  in  dollars  and  cents;  often 
it  is  necessary  to  spend  time  with  them  in  which  little  or  nothing 
is  done ;  time  for  which  one  will  not  feel  like  making  a  proper 
charge.  In  many  cases  this  is  necessary.  Often  when  a  child  is 
first  brought  to  the  dentist  he  should  only  temporize;  not  try 
to  do  this  or  that  operation  which  seems  necessary  at  the  time, 
but  do  something  to  the  mouth  or  to  the  teeth,  something  that 
will  lead  the  child  to  suppose  that  an  operation  has  been  success- 
fully begun;  not  something  to  deceive,  but  something  to  gain 
the  confidence  of  the  child ;  one  should  never  deceive  a  child.  If 
it  is  necessary  to  hurt  a  child,  say  so.  Usually,  with  children,  a 
deception  is  fatal  to  after-success.  A  dentist  should  not  allow 
parents  to  deceive  children  in  his  office.  Often  the  greatest  diffi- 
culty in  the  management  of  children  is  the  management  of  the 
parents.  Parents  should  not  deceive  their  children  with  regard 
to  these  operations.  To  tell  a  child  it  will  not  be  hurt,  and  then 
inflict  severe  pain,  is  doing  that  child  a  wrong;  it  is  lessening 
that  child's  confidence  in  humanity;  and  children  ought  to  grow 
up  with  confidence  in  the  integrity  and  honesty  of  those  about 
them. 

Relation  of  Growth  and  Shedding  of  the  Deciduous  Teeth  to 

Their  Treatment. 

While  the  main  difficulties  in  the  management  of  children's 
teeth  are  in  the  directions  indicated  above,  there  are  matters  per- 
taining to  the  progress  of  development  of  the  deciduous  teeth, 
the  absorption  of  their  roots  in  the  process  of  shedding,  their 
replacement  by  the  permanent  teeth  and  the  development  of  the 
roots  of  these,  that  must  have  careful  consideration  at  every  step 
of  operations  upon  the  teeth  of  children.    Considered  from  this 


238  PATHOLOGY    OF    THE    HABD    TISSUES    OF    THE    TEETH. 

standpoint,  we  should  regard  all  persons  under  fourteen  or  fif- 
teen years  old  as  children ;  for  the  development  of  the  permanent 
teeth,  exclusive  of  the  third  molars,  which  we  need  not  consider, 
is  not  completed  until  about  that  time. 

The  deciduous  teeth  of  one  side  of  the  upper  jaw  are  repre- 
sented in  outline  considerably  enlarged  in  Figures  172,  173.  In 
the  first  of  these,  the  growth  of  the  crowns  and  the  roots  of  the 
teeth  is  represented  by  figures  placed  upon  the  individual  teeth. 
In  the  second,  the  absorption  of  the  roots  of  the  deciduous  teeth 
is  represented  in  a  similar  way.  The  two,  taken  together,  give  a 
brief  synopsis  of  the  changes  which  take  place,  together  with  the 
average  time  in  years  occupied.  The  calcification  of  the  decidu- 
ous teeth,  according  to  this  chart,  Figure  172,  begins  in  the 
central  incisor  at  about  the  seventeenth  week  of  uterine  life. 
Eeading  from  left  to  right,  the  position  of  the  0  on  the  various 
teeth  represents  the  average  calcification  at  birth,  the  figure  1 
represents  the  growth  of  the  roots  at  one  year,  the  figure  2  the 
growth  at  two  years,  and  the  figure  3  at  three  years,  when  the 
growth  of  all  of  the  roots  of  this  set  of  teeth  are  complete.  It 
must  be  understood  that  this  is  a  representation  of  averages  from 
which  there  are  wide  variations.  Also,  that  it  has  little  to  do 
with  the  time  of  cutting,  erupting  or  presentation  of  the  teeth 
through  the  gums.  The  time  of  this  is  probably  more  variable 
than  the  process  of  calcification.  Yet,  careful  study  of  cases 
shows  that  there  is  a  fair  relation  between  the  calcification  and 
the  cutting  of  both  the  deciduous  and  permanent  teeth  that  is  of 
much  value  in  the  management  of  cases  when  the  history  can  be 
obtained.  While  it  does  not  invariably  follow,  it  is  so  with  suffi- 
cient frequency  that  we  may  reasonably  expect  that  if  the  teeth 
of  a  child  have  been  very  late  in  erupting,  the  completion  of  the 
calcification  (the  growth)  of  the  roots  will  also  be  later  than  the 
average  time.    This  history  is  often  of  great  value. 

Prematuke  ERUPTIONS  OP  TEETH.  Occasioually  cases  of  pre- 
mature eruption  of  teeth  have  been  noted,  i.  e.,  cases  in  which  the 
crowns  have  protruded  through  the  gums  before  sufficient  root 
has  formed  to  serve  as  support  to  the  crown,  and  as  a  conse- 
quence the  crown  has  been  displaced.  Within  the  observation  of 
the  author,  this  has  occurred  only  with  the  incisors.  In  one  the 
central  incisors  were  found  erupted  at  birth.  Other  cases  have 
been  noted  in  which  the  teeth  were  erupted  before  there  was  suf- 
ficient growth  of  dentin  to  form  sufficient  root  to  maintain  them 
in  position.  These  latter  have  in  each  case  been  a  single  central 
incisor  erupted  soon  after  birth  and  much  in  advance  of  the  other 


Fio.  172.  Diagram  of  the  deciduous  tcctn,  cunsklerably  enlarged,  representing  tlie  progress  ol 
their  calcification.  0,  placed  upon  the  individual  teeth  represents  the  progress  of  calcification  at  birth. 
The  figures  1,  2  and  3  represent,  in  years,  the  progress  of  the  calcification  of  each  tooth.  The  inten- 
tion is  to  represent  averages.     It  must  be  understood  that  considerable  variations  will  be  found. 

Fig.  173.  Diagram  of  the  deciduous  teeth  considerably  enlarged,  representing  the  absorption  of 
the  roots.  The  figure  placed  over  each  tnolh  n  prcsrnts,  in  years,  the  average  time  of  the  beginning  of 
the  absorption  of  its  roots.  The  figures  placed  upon  the  roots  of  the  teeth  represent,  in  years,  the 
progress  of  the  absorption  of  the  roots  of  the  several  teeth.  Considerable  variation  from  the  general 
average,  and  also  in  the  order  of  progress,  must  be  expected.  Not  infrequently  the  absorption  of  the 
root  of  the  second  molar  is  completed  before  the  completion   of   the  first. 


MANAGEMENT   OF   CHILDREN'S   TEETH.  239 

teeth.    These  are  supposed  to  have  been  due  to  accidental  mal- 
positions of  the  developing  teeth. 

We  may  fill  the  roots  of  deciduous  teeth  after  removing 
the  pulps  that  have  become  exposed  from  caries,  or  other  cause, 
the  same  as  we  may  fill  the  roots  of  permanent  teeth.  But  it 
would  be  manifestly  wrong  to  place  arsenic  in  such  a  tooth  to 
destroy  a  pulp  or  to  undertake  to  remove  a  dead  pulp,  treat  and 
fill  roots  in  these  teeth  before  the  roots  have  completed  their 
growth  and  the  pulp  canals  have  been  narrowed  to  minute  open- 
ings. Such  a  condition  necessarily  defeats  the  success  of  the 
procedure.  Happily,  we  are  seldom  presented  with  cases  seem- 
ing to  call  for  such  an  operation  at  so  early  an  age,  but,  occa- 
sionally, these  do  occur.  Then,  if  the  age  is  close  to  the  time  of 
the  completion  of  the  roots,  a  history  of  the  age  at  which  the 
deciduous  teeth  were  erupted  becomes  of  especial  importance  in 
the  prognosis,  and  should  often  determine  whether  or  not  such 
an  operation  should  be  undertaken. 

ABSORPTION   OP   THE   ROOTS   OF   THE   DECIDUOUS   TEETH. 

The  next  difficulty  encountered  is  the  absorption  of  the  roots 
of  the  deciduous  teeth  preparatory  to  the  shedding  process.  This 
is  shown  in  brief  in  Figure  173.  In  this,  the  average  date,  in 
years,  in  the  life  of  the  child,  of  the  beginning  of  the  absorption 
is  placed  over  each  tooth.  The  progress  of  absorption,  in  years, 
is  represented  in  figures  placed  on  the  root  of  each  tooth  at  the 
point  to  which  absorption  has  progressed,  which  may  be  read  for 
each  individual  tooth  at  a  glance.  These  figures  represent  aver- 
ages from  which  there  are  wide  variations.  Of  late,  certain 
writers  have  used  the  phrase  ' '  decalcification  of  the  roots  of  the 
deciduous  teeth,"  to  which  there  is  serious  objection.  We  should 
use  either  the  word  absorption,  or  resorption  —  not  decalcifica- 
tion. If  we  place  a  tooth  in  a  weak  solution  of  an  acid,  it  will 
be  decalcified  —  i.  e.,  the  calcium  salts,  the  substance  which  gives 
the  tooth  its  hardness,  will  be  dissolved  out,  leaving  the  body  of 
the  tooth,  the  basic  animal  substance,  remaining.  In  this,  the 
normal  physical  and  histological  form  of  the  dentin  is  preserved 
in  its  completeness.  In  caries  of  the  teeth  the  dentin  is  first 
decalcified  by  an  acid,  leaving  a  softened  mass  which  is  afterward 
decomposed,  forming  a  cavity.  Decalcification  means  something 
entirely  different  from  what  we  mean  by  the  word  absorption,  as 
used  to  represent  the  physiological  removal  of  the  roots  of  decid- 
uous teeth,  or  the  removal  of  bone,  or  of  catgut  ligatures  used  in 


240  PATHOLOGY   OF   THE   HAED   TISSUES   OF   THE   TEETH. 

surgery,  etc.  In  the  absorption  of  the  roots  of  the  teeth,  or  any 
of  these  substances,  the  whole  of  the  tissue  is  removed  complete 
without  a  perceptible  softening  in  advance.  The  whole  process 
is  something  entirely  different  from  what  we  know  as  decalcifi- 
cation. 

Absorption  of  the  root  of  the  central  incisor  begins,  practi- 
cally, when  the  child  is  four  years  old  and  is  ended  at  seven.  The 
lateral  incisor  begins  to  be  absorbed  at  five  years  and  is  ended  at 
eight.  The  absorption  of  the  root  of  the  first  deciduous  molar 
is  begun  at  seven  and  completed  at  ten  years.  The  second  molar 
has  begim  to  be  absorbed  at  eight  and  is  completed  at  eleven. 
The  absorption  of  the  cuspid  root  begins  at  about  nine  years 
and  is  completed  at  twelve.  In  the  formulation  of  this  state- 
ment, it  has  been  the  endeavor  to  put  it  in  a  form  that  will  be 
easily  remembered.  (1)  In  the  absorption  of  the  roots  of  the 
deciduous  teeth  the  incisors  begin,  the  central  at  four,  the  lateral, 
five;  (2)  skip  a  tooth  and  a  number  and  the  molars  begin  to  be 
absorbed,  the  first  at  seven,  the  second  at  eight;  (3)  skip  back 
to  the  cuspid  which  begins  to  be  absorbed  at  nine  years. 

There  is  a  difference  in  time  in  the  absorption  of  roots  of 
teeth  between  different  individuals.  Some  will  be  a  year  or  so 
early  or  as  much  late.  Also,  the  time  between  the  individual 
teeth  of  the  person  may  be  considerable.  Perhaps  this  four  and 
five  years  for  the  central  and  lateral  is  not  quite  the  average; 
four  and  four  and  a  half  would  be  more  nearly  the  average ;  but 
this  is  a  figure  that  is  easily  remembered  and  is  placed  in  that 
way,  as  being  the  closest  proximation  in  whole  numbers.  Occa- 
sionally the  lateral  incisors  fall  away  before  the  centrals,  but 
that  is  rare.  Often  they  fall  away  about  the  same  time,  or  very 
close  together ;  not  six  months  between.  Often  again,  there  will 
be  two  years  between.  With  the  molars  it  is  the  same  way. 
Often  the  second  bicuspid  will  be  in  place  before  the  first  bicus- 
pid, the  molars  having  fallen  away  in  this  order.  All  of  these 
differences  may  be  found.  It  does  not  run  absolutely  as  repre- 
sented in  the  illustration,  but  this  represents  a  fair  approxima- 
tion to  the  average. 

When  the  absorption  of  the  root  of  a  tooth  has  proceeded 
some  little  distance,  it  would  be  improper  to  place  arsenic  in  that 
tooth  for  the  purpose  of  destroying  the  pulp.  While  the  root  is 
complete,  arsenic  may  be  used  for  destroying  pulps  in  the  decidu- 
ous just  the  same  as  in  the  permanent  teeth,  but  one  must  have 
a  care  as  to  the  time  at  which  arsenic  is  used.  Furthermore,  if 
the  root  of  a  tooth  is  absorbed  half  way,  a  root  filling  could  not 


MANAGEMENT    OF    CHILDREN'S    TEETH.  241 

be  made  successfully  if  the  pulp  was  destroyed  and  removed. 
The  root  canal  would,  in  most  cases,  have  a  wide  open  end  that 
would  interfere  with  this  operation.  One  must  be  on  guard  con- 
tinually as  to  that.  One  must  have  in  mind  a  clear  conception  of 
the  conditions  in  the  case  in  the  placing  of  arsenic  or  in  attempt- 
ing to  fill  roots  of  temporary  teeth.  We  may  fill  the  roots  of 
temporary  teeth  before  the  absorptive  process  begins,  just  the 
same  as  the  roots  in  permanent  teeth.  The  absorptive  process 
will  go  on  at  the  proper  time ;  the  root  filling  will  stand  up  in  the 
tissues,  produce,  apparently,  no  irritation,  and  the  absorption 
will  go  on  just  the  same  as  it  will  in  a  tooth  with  a  living  pulp. 
These  little  molars,  the  roots  of  which  have  been  filled  in  this 
way,  come  away  with  the  three  legs  of  root  filling  —  gutta-percha 
or  gold,  standing  up  in  the  tissue,  seeming  to  have  produced  no 
irritation  whatever. 

ACCIDENTS  DURING   ABSOEPTION  OF   BOOTS  OF  THE  DECIDUOUS  TEETH. 

A  number  of  what  we  may  call  accidents,  occur  during  this 
absorption  of  the  roots  of  temporary  teeth.  First,  if  there  is  an 
alveolar  abscess  at  the  root  of  a  temporary  tooth  and  that  abscess 
is  continuing  in  a  chronic  form,  the  rule  is  that  absorption  of  the 
root  will  fail.  The  death  of  the  pulp  of  the  tooth  does  not  inter- 
fere with  the  absorptive  process.  The  question  is  simply  as  to 
the  condition  of  the  tissues  about  the  end  of  the  root.  The 
absorption  of  these  roots  is  a  physiological  process,  and,  in  order 
for  it  to  progress  properly,  the  tissues  about  the  root,  the  peri- 
dental membrane,  must  be  in  a  physiological  condition.  If  dis- 
ease is  going  on  there,  such  as  we  have  in  alveolar  abscess,  the 
absorptive  process  will  be  defeated  and  different  kinds  of  trouble 
come  up  on  account  of  it.  Often  a  tooth  is  bodily  pushed  out  of 
the  way,  the  other  tooth  taking  its  place,  seemingly,  by  physical 
force.  In  other  cases,  the  permanent  tooth  is  deflected  from  its 
proper  position.  The  apical  end  of  the  root  of  a  central  incisor 
is  occasionally  pushed  labially,  while  its  neck  is  held  nearly  in 
normal  position.  Less  frequently  the  same  thing  may  happen 
to  a  lateral  incisor  or  a  cuspid,  but  the  forms  of  the  teeth  replac- 
ing these  are  such  that  they  are  more  liable  to  slip  to  one  side 
and  be  deflected  from  their  normal  positions.  The  broad  cutting 
edge  of  the  central  incisor  is  that  which  most  frequently  pushes 
the  root  of  the  deciduous  tooth  labially,  causing  the  end  of  the 
root  to  protrude  through  the  gum  and  sometimes  into  the  lip  of 
the  child.  These  cases  are  not  very  frequent,  and  yet  they  are 
sufficiently  frequent  that  we  should  recognize  them  when  they 


242  PATHOLOGY   OF    THE    HABD    TISSUES    OF    THE    TEETH. 

present.  In  case  of  alveolar  abscess,  the  bone  about  the  end  of 
the  root  will  be  absorbed,  leaving  an  opening  in  which  there  is 
only  soft  tissue.  The  crown  of  the  permanent  tooth  comes  down, 
moving  forward  and  downward,  and  strikes  the  lingual  side  of 
the  root  of  the  temporary  tooth  and  begins  to  push  it  away,  as 
shown  in  Figures  174,  175,  176.  A  pathological  condition  here 
prevents  the  absorption  of  the  root;  pus  is  lying  aroimd  it 
instead  of  normal  tissue.  The  result  is  that  the  apical  end  of 
the  root  of  the  deciduous  tooth  is  gradually  pushed  over  to  the 
labial,  and  the  permanent  tooth  following  up,  the  end  of  the 
root  of  the  deciduous  tooth  is  finally  tipped  out  through  the  gums, 
under  the  lip,  as  illustrated  in  Figure  175,  and,  occasionally,  cuts 
into  the  lip,  as  shown  in  Figure  176.  Whenever  the  examination 
of  a  child  near  the  age  at  which  the  deciduous  incisors  are  shed, 
reveals  a  sore  point  under  the  lip  and  some  bony  sul)stance 
appearing  in  the  tissues,  it  should  at  once  be  supposed  to  be  the 
apex  of  the  root  of  the  deciduous  incisor,  and,  placing  an  instru- 
ment upon  that  and  a  finger  upon  the  stump  of  the  incisor,  and 
moving  it  a  little,  it  will  be  found  that  they  move  together,  which 
will  confirm  the  diagnosis.  Then,  of  course,  the  remedy  is  to 
extract  the  root.  It  will  generally  be  found  that  the  permanent 
tooth  is  pushing  the  root  out  of  its  way.  This  will  be  met  in 
practice  quite  often  if  one  has  many  children  to  deal  with.  In 
the  author's  practice  some  years  ago,  a  slight  little  girl  was  pre- 
sented in  whom  a  sore  under  the  lip  from  this  cause  had  been 
neglected  until  the  lip  had  been  cut  through  and  the  apex  of  the 
root  was  found  in  the  "running  sore"  on  the  skin  under  the  nos- 
tril. At  the  time,  the  little  girl  was  very  thin  in  flesh,  anemic, 
and  had  a  temperature  of  101  degrees.  Yet,  the  sore  seemed  in  a 
chronic  condition  without  any  extended  inflammation  or  swelling. 
It  was  reported  to  me  that  a  physician  had  been  looking  after 
the  case  for  some  weeks,  evidently  without  discovering  the  cause 
of  the  difficulty  with  the  lip. 

In  the  absorption  of  the  roots  of  the  deciduous  molars,  a 
difficulty  is  found  that  is  somewhat  different.  Often  the  crown 
of  the  bicuspid  will  come  between  these  wide-spreading  roots, 
the  roots  will  be  absorbed  only  near  their  junction  with  the 
crown,  and  the  ends  of  the  roots  will  be  loft  unabsorbed.  These 
will  be  found  sticking  in  the  alveolar  process  or  gums  after  the 
bicuspid  has  taken  its  place;  sometimes  abscesses  occur  in  con- 
sequence of  this,  or  occasionally  considerable  soreness  without 
abscess.  Occasionally  the  unabsorbed  portion  of  the  root  will 
remain  between  the  bicuspid  and  the  proximating  tooth,  expand- 


Fio.  174. 


Fio.  175. 


Fia.  176. 


Figs.  174-176.  Diagr-inimatic  representation  of  a  condition  whicli  occasionally  occurs,  when, 
because  of  pathological  conditions  about  the  apex  of  the  root  of  a  deciduous  incisor,  absorption  of  the 
root  fails.  Figure  174.  The  permanent  incisor  moves  downward  and  forward  to  assume  its  position 
in  the  arch  and  strilics  the  lingual  surface  of  the  root  of  the  deciduous  tooth  near  its  apex.  Figure 
175.  In  the  continued  movement  of  the  permanent  incisor  the  apex  of  the  root  of  the  deciduous  tooth 
is  tipped  to  the  labial  and  pushed  through  the  gum  tissues  under  the  lip.  AVhon  this  is  allowed  to 
continue,  a  condition  shewn  in  Figure  176  is  li.ablc  to  occur,  in  which  the  apex  of  the  root  of  the 
deciduous  tooth  gradually  works  its  way  into  the  lip  itself,  resulting  in  suppuration. 


MANAGEMENT    OF    CHILDREN'S    TEETH.  243 

ing  the  arch  and  making  room  for  itself.  These  are  usually 
easily  removed  if  the  conditions  are  recognized.  They  produce 
very  much  less  trouble  than  the  roots  of  incisors.  Recently  a 
student  brought  me  a  lower  first  and  a  lower  second  bicuspid, 
which  he  had  just  extracted,  to  ask  an  explanation  regarding  a 
singular  growth  on  the  proximal  side  of  the  apex  of  the  root  of 
each  one  of  the  teeth.  TJpon  examination,  I  found  each  of  these 
to  be  the  apical  half  almost  entire  of  the  roots  of  a  deciduous 
molar,  or  possibly  of  the  distal  root  of  each  deciduous  molar 
that  had  remained  in  the  jaw  and  had  become  attached  in  this 
way.  One  of  them  was  slightly  movable,  and  therefore  was 
attached  only  by  the  fibers  of  the  peridental  membrane,  though 
the  attachment  was  very  firm.  The  other  was  immovable  and 
was  evidently  attached  by  cementum.  No  history  of  any  difficulty 
from  these  retained  bits  of  roots  was  discoverable.  Occasionally 
the  root  of  a  cuspid  will  be  found  —  a  long  root  —  being  thrown 
out  under  the  lip  in  the  same  way  as  the  incisors.  This  root  is 
occasionally  so  long  that  its  end  will  be  too  high  to  pass  out  under 
the  lip  and  the  labial  side  of  it  will  appear  in  the  opening. 

Occasionally  an  abscess  will  occur  at  the  end  of  tlie  root  of  a 
temporary  molar  before  the  enamel  of  the  crown  of  the  bicuspid 
has  been  completed,  and,  in  that  case,  the  pus  may  break  into 
the  enamel  organ  and  destroy  it,  or  a  part  of  it,  so  that  the 
enamel  of  the  crown  of  the  bicuspid  will  never  be  completed. 
Then  it  will  come  through  as  an  imperfectly  enameled  tooth.  I 
have  observed  a  number  of  these  cases,  one  in  my  own  family, 
where  an  abscess  occurred  very  early  at  the  root  of  a  temporary 
molar,  in  which  there  was  a  good  deal  of  swelling  and  a  good 
deal  of  pus.  I  suspected  at  the  time  that  there  would  be  injury 
to  the  bicuspid,  and  when  the  bicuspid  presented  the  enamel 
was  imperfectly  formed,  not  having  been  completed.  This  has 
occurred  a  number  of  times  under  my  personal  observation. 
Sometimes  these  injuries  closely  resemble  atrophy  in  appear- 
ance, but  are  readily  distinguished  from  that  class  of  injury  by 
being  confined  to  one  or  two  teeth.  But  it  is  only  occasionally 
that  we  get  injury  from  alveolar  abscess  that  has  occurred  quite 
early  at  the  root  of  a  temporaiy  tooth. 

Not  very  infrequently  the  failure  of  absorption  of  an 
abscessed  temporary  molar  will  hold  back  and  delay  the  eruption 
of  a  bicuspid ;  and  it  is  often  difficult  to  determine  the  cause  of 
this  delay  satisfactorily  without  an  X-ray  picture.  This,  how- 
ever, will  show  the  condition  clearly  enough  to  complete  the 
diagnosis.    These  cases  illustrate  the  peculiar  value  of  keeping 


244  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE   TEETH. 

accurate  records  of  cases.  A  severe  alveolar  abscess  may  occur 
early  at  the  root  of  a  deciduous  molar,  be  relieved  by  discharge 
of  the  pus,  or  the  removal  of  the  offending  tooth,  and  be  forgot- 
ten. When  the  bicuspid  takes  its  place  with  imperfect  enamel, 
no  one  knows  what  has  occurred.  If  there  is  a  record  of  the  prior 
condition  and  the  treatment,  the  two  incidents  become  properly 
connected  as  cause  and  effect.  A  number  of  cases  have  occurred 
in  the  author's  practice  in  which  necrosis,  as  a  result  of  these 
abscesses,  has  brought  away  the  permanent  tooth  with  that  por- 
tion of  bone  immediately  surrounding  it.  These  things  lead  one 
to  believe  that  the  sufferings  of  children  with  these  conditions 
are  not  sufficiently  appreciated.  It  is  certain  that  the  little  ones 
are  much  too  often  neglected. 

The  absorptive  process  seems  to  be  very  fickle  in  its  begin- 
ning and  in  its  progress,  and  there  are  many  cases  of  variation 
from  the  normal.  In  some  of  these,  the  absorptive  process  seems 
to  be  hurried  and  it  will  be  completed  before  the  normal  time  so 
that  a  temporary  tooth  will  drop  away  before  the  permanent 
tooth  has  come  forward,  and  the  child  may  be  without  a  tooth 
for  a  year  or  two ;  whereas,  in  the  normal  process,  when  the  little 
tooth  drops  away,  the  permanent  tooth  should  present  at  once. 
These  cases  are  not  so  frequent,  however,  as  delayed  absorption. 
Delayed  absorption  of  roots  occurs  quite  often,  so  that  the  com- 
ing tooth  will  be  deflected  from  its  position.  If  the  absorption 
of  a  root  of  a  lateral  incisor  or  cuspid  is  delayed,  the  coming  tooth 
will  generally  strike  its  lingual  surface  and  be  deflected  to  the 
lingual.  Deflections  to  the  labial  are  more  likely  to  occur  from 
other  causes,  but  deflections  to  the  mesial  or  distal,  the  tooth 
making  room  in  the  arch  for  both  itself  and  the  retained  decidu- 
ous tooth,  are  occasionally  seen.  In  case  of  the  bicuspids,  the 
crowns  are  normally  between  the  spreading  roots  of  the  decidu- 
ous molars,  and  in  case  the  absorption  is  delayed,  generally  the 
coming  bicuspid  is  simply  held  back.  In  the  upper  jaw  it  may 
escape  from  between  the  spreading  buccal  roots  and  be  deflected 
to  the  buccal,  so  that  the  tooth  will  come  out  to  the  buccal  of 
its  normal  position  in  the  arch.  In  the  lower  jaw  they  may  be 
deflected  either  to  the  buccal  or  to  the  lingual,  but  they  are  more 
generally  simply  delayed,  held  back  by  the  lack  of  absorption 
of  the  roots.  Indeed,  the  absorption  of  the  roots  of  the  tem- 
porary teeth  does  not  soem  to  be  especially  stimulated  by  the 
coming  of  the  permanent  teeth,  for  they  are  often  absorbed 
when  there  is  no  permanent  tooth  to  come.  When  that  happens, 
the  absorption  occurs  in  accord  with  a  process  of  nature,  and 


MAKAGEMENT    OF    CHILDREN'S    TEETH.  245 

this  i^rocess  is  varied  somewhat,  as  I  have  stated.  In  the  case 
where  a  permanent  tooth  fails  to  develop,  which  occurs  occa- 
sionally with  the  lateral  incisors,  the  absorptive  process  will 
generally  go  on  and  the  little  tooth  drop  away,  notwithstanding 
the  fact  that  there  is  no  permanent  tooth  to  take  its  place.  The 
cuspid  tooth,  on  the  other  hand,  generally  remains  if  there  is 
no  permanent  tooth  coming  forward  to  take  its  place.  If  the 
cuspid  happens  to  be  deflected  from  its  position  from  some  other 
cause,  or  becomes  impacted  within  the  bone  by  taking  a  wrong 
direction,  the  deciduous  cuspid  often  remains  in  its  place,  the 
absorption  only  partially  removing  the  root,  and  may  be  foimd 
in  its  place  on  up  to  middle  life,  and  in  a  few  cases  it  may  be 
seen  continuing  in  its  position  and  doing  service  until  old  age. 

These  retained  deciduous  cuspid  teeth  require  somewhat 
careful  handling.  It  is  often  difficult  for  us  to  know  whether 
the  permanent  tooth  is  likely  to  come  forward  later  or  not. 
The  author  has  seen  them  come  forward  as  late  as  twenty,  and 
in  one  case  in  which  the  person  was  twenty-five  years  old,  but 
generally,  if  they  do  not  come  forward  somewhere  near  their 
normal  time,  we  need  not  expect  them.  Often  much  light  may 
be  thrown  on  this  by  an  X-ray  picture,  which  will  show  the  posi- 
tion of  the  permanent  cuspid.  If  it  is  not  present  that  fact 
may  be  determined.  It  is  often  important  that  we  retain  these 
deciduous  cuspids,  not  only  for  the  appearance,  but  for  the  real 
service  that  they  will  do,  and  as  they  are  liable  to  decay  the 
same  as  other  teeth,  they  require  filling. 

In  handling  these  teeth,  any  considerable  disturbance  is 
likely  to  hasten  the  absorptive  process  and  cause  the  tooth  to 
loosen  and  fall  away,  or  at  least  it  has  been  observed  in  a 
number  of  cases  where  these  deciduous  cuspids,  that  seemed 
quite  firm  in  their  position,  have  fallen  away  soon  after  a  filling 
was  made.  This  observation  has  occurred  so  often  as  to  sug- 
gest strongly  that  a  considerable  disturbance  of  the  peridental 
membrane  by  much  malleting  is  very  liable  to  start  up  this 
absorptive  process  afresh  and  cause  the  loss  of  the  tooth.  There- 
fore, when  it  is  necessary  to  make  fillings,  these  teeth  should  be 
handled  very  cautiously. 

Occasionally  we  find  temporary  molars  remaining  in  posi- 
tion, and,  in  a  few  instances,  a  bicuspid  is  seen  deflected  mesially 
or  distally  and  takes  its  place  beside  the  temporary  molar ;  but, 
generally,  if  they  are  deflected  at  all,  they  will  be  deflected  to 
the  buccal  in  the  upper  jaw  or  to  either  the  buccal  or  lingual  in 
the  lower.    These  teeth  do  not  often  remain  so  late  in  life  as 


246  PATHOLOGY   OF    THE    HARD    TISSUES    OF    THE   TEETH. 

the  cuspids,  yet  I  remember  one  case  in  which  the  patient  had 
one  deciduous  molar  still  remaining  when  he  died,  at  about 
seventy-two.  This  little  tooth  had  done  service  all  these  years, 
and,  of  course,  where  there  is  a  possibility  that  a  deciduous 
tooth  will  do  this  kind  of  service,  it  is  important  that  it  have 
the  best  treatment  we  can  give  it. 

Latterly,  the  X-ray  has  come  to  be  of  great  value  to  us. 
A  picture  will  determine  the  position  of  impacted  teeth,  and 
in  this  way  information  is  gained  that  will  be  of  great  value 
to  us  in  determining  whether  or  not  a  deciduous  tooth  should 
be  retained.  Generally,  if  an  X-ray  shows  the  permanent  tooth 
in  proper  position,  and  apparently  held  back,  the  proper  treat- 
ment will  be  the  extraction  of  the  temporary  tooth,  with  the 
expectation  that  the  permanent  tooth  will  come  forward;  gen- 
erally it  will.  Heretofore  we  have  not  had  the  opportimity  to 
make  this  observation.  If  the  permanent  tooth  was  in  its  normal 
position,  it  was  very  difficult  to  tell  whether  it  was  there  at  all 
or  not  by  any  examination  we  could  make,  previous  to  the  dis- 
covery of  the  X-ray.  If  it  is  deflected  somewhat  to  one  side 
or  the  other,  we  will  find  an  enlargement  that  will  enable  us 
to  detect  its  presence.  Therefore,  it  is  advised,  where  it  becomes 
important  as  to  the  treatment  of  a  retained  deciduous  tooth, 
that  an  X-ray  be  made  in  order  to  imderstand  better  the  posi- 
tion of  the  permanent  tooth. 

A  somewhat  singular  phenomenon  occurs  occasionally  with 
deciduous  teeth  that  have  been  retained  longer  than  the  usual 
time  of  shedding.  This  is  most  often  seen  in  the  molars.  The 
general  rule  is  that,  when  these  teeth  are  not  shed  at  the  usual 
time,  they  are  carried  upward  (toward  their  occluding  teeth)  by 
the  growth  of  the  bones,  and  remain  in  occlusion.  Sometimes, 
however,  this  seems  to  have  failed  and  the  deciduous  molar,  or 
the  two  of  them,  retain  their  position  in  the  bone,  and  the  growth 
of  the  jaws  and  the  movement  of  the  permanent  teeth  carry 
the  occlusion  away  from  them.  These  teeth  are  then  often 
almost  overgrown  by  the  gums.  I  have  models  of  a  case  in 
which  all  of  the  deciduous  molars  were  retained  in  this  way 
in  a  boy  almost  fifteen  years  old.  The  occlusal  surfaces  lacked 
eight  and  one-half  millimeters  (one-third  of  an  inch)  of  coming 
into  occlusion,  when  the  permanent  teeth  were  closed  together. 

In  the  ease  just  cited,  X-ray  pictures  were  made  which 
showed  the  bicuspids  in  place  between  the  roots  of  the  deciduous 
molars.  These  teeth  were  then  removed.  Only  a  little  absorp- 
tion had  occurred  in  the  crotch  formed  by  the  spreading  roots, 


MANAGEMENT    OP    CHILDKEN 's    TEETH.  247 

and  the  crowns  of  the  bicuspids  were  found  uncovered  in  the 
wound.  Generally  such  teeth  should  be  removed  at  once  if  the 
X-ray  shows  the  succedaneous  teeth  in  proper  position. 

Occasionally  these  cases,  as  the  one  just  cited,  give  an  object 
lesson  in  the  movements  of  the  teeth  that  are  made  concurrent 
with  and  forming  a  part  of  the  movements  in  the  lengthening 
of  the  face,  which  occurs  in  the  change  from  the  child  to  the 
adult. 

Treatment  of  Caries  of  the  DEcrouous  Teeth. 

This  is  one  of  the  most  difficult  subjects  in  dentistry.  Not 
that  caries  in  these  teeth  is  in  any  wise  different  from  caries 
of  the  permanent  teeth,  but  the  conditions  under  which  we 
must  treat  caries  of  the  deciduous  teeth  are  very  different  from 
the  conditions  under  which  we  treat  caries  in  the  teeth  of  adults. 
"We  have  the  child  to  deal  with,  and  occasionally  the  little  child, 
for  we  may  find  caries  beginning  in  their  teeth  as  early  as  two 
years  old,  and  occasionally  earlier.  When  it  occurs  so  early, 
we  may  feel  certain  that  caries  is  going  to  be  very  severe  and 
that  it  will  destroy  the  teeth  quickly  unless  some  remedy  that 
is  effectual  is  used.  And  the  question  is,  how  are  we  to  apply 
our  remedy  to  the  teeth  of  the  baby?  None  of  us  like  to  hurt 
a  child ;  none  of  us  like  to  perform  such  an  operation  as  seems 
to  be  required  by  force  against  its  struggles  and  its  cries.  Just 
there  is  the  difficulty,  and  it  is  practically  the  only  difficulty, 
so  far  as  making  fillings  is  concerned.  We  may  make  fillings 
in  these  teeth  just  as  well  as  in  the  adult  teeth ;  there  is  nothing 
in  the  condition  of  the  tissues  of  the  teeth  that  will  hinder  mak- 
ing these  fillings,  and  if  the  extensions  are  made  sufficient  to 
protect  the  area  of  liability  to  decay,  fillings  will  stand  well. 
True,  none  of  us  have  observed  so  many  fillings  for  these  little 
folks  as  for  grovm-up  people,  but  enough  of  them  have  been 
observed  for  us  to  feel  sure  of  this  statement  from  the  clinical 
standpoint.  This  is  strongly  supported  from  physical  examina- 
tion of  the  teeth.  The  technical  procedures  in  making  fillings 
in  these  teeth  would  be  the  same  as  in  making  like  fillings  in 
the  teeth  of  adults  and  will  not  be  discussed  here.  Where  we 
find  conditions  in  which  we  can  make  fillings,  we  should  not 
hesitate  to  make  them. 

The  general  rule  is  that  we  can  not  make  metallic  fillings 
for  these  little  folk;  we  will  have  to  resort  to  other  methods. 
In  many  cases  we  can  not  reasonably  make  the  proper  excava- 
tion.   These  teeth  are  as  painful  as  the  teeth  of  older  people, 


248  PATHOLOGY    OF    THE    HAHD    TISSUES    OF    THE   TEETH. 

and  our  sympathy  for  the  child  will  prevent  us  from  doing  that 
which  seems  necessary  to  be  done.  We  must  temporize  in  our 
treatment.  How  can  we  temporize  to  advantage,  becomes  the 
question.  Can  we  make  successful  use  of  prophylaxis  by  arti- 
ficial cleaning  of  the  areas  of  liability  to  caries  and  in  this  way 
prevent  caries!  In  highly  susceptible  families,  this  would  have 
to  be  begun  very  early  to  be  successful.  While  the  teeth  should 
be  kept  generally  clean,  the  more  especial  attention  should  be 
confined  to  the  areas  of  liability.  These  are  occasionally  found 
with  beginning  decay  of  the  enamel  within  a  few  montlas  after 
they  come  through  the  gums.  Is  it  possible  to  handle  these  bad 
cases  in  this  cleaning  process  ?  Those  who  are  especially  inter- 
ested in  the  development  of  this  method  of  combating  caries 
will  do  well  to  try  handling  the  little  ones  in  very  susceptible 
families. 

TREATMENT    OF    DECAYS    OF    THE    DECIDUOUS    INCISOBS    AND    CUSPIDS. 

In  consideration  of  other  methods,  there  are  certain  con- 
ditions peculiar  to  the  child  that  are  important  for  us  to  consider. 
We  may  say  that  by  the  end  of  the  third  year  (speaking  of  the 
deciduous  incisors  and  cuspids  particularly),  the  growth  of  the 
jaws  and  the  development  of  the  permanent  teeth  in  the  region 
of  the  roots  of  the  deciduous  incisors  have  begun  to  carry  these 
little  teeth  slightly  apart ;  at  least,  the  effect  of  the  growth  will 
prevent  these  teeth  from  dropping  together  if  the  contacts  are 
cut  away  at  this  age.  And,  as  the  child  grows  older,  the  ten- 
dency is  for  these  teeth  to  stand  apart.  This  we  can  take  advan- 
tage of  in  the  treatment  and  do  that  which  we  can  not  do  with 
the  permanent  teeth.  We  can  cut  them  apart  freely,  make  spaces 
between  them,  and  these  spaces  will  be  self -cleaning  and  remain 
permanent;  that  is,  after  the  child  is  about  three  years  old. 
The  teeth  will  then  be  in  contact  as  shown  somewhat  enlarged 
in  Figures  177,  178.  One  of  the  best  methods  of  treatment  for 
decays  of  slight  depth  that  have  started  in  the  proximal  sur- 
faces of  the  incisors  or  the  mesial  surfaces  of  the  cuspids  —  such 
as  are  shown  in  Figures  179,  180,  is  to  file  them  out,  or  file  them 
partly  out.  With  a  small  chisel  or  an  8-3-6  hoe  excavator,  chip 
away  the  undermined  enamel.  Make  the  cavity  as  broad  as 
possible  in  that  way  so  as  to  reduce  the  amount  of  filing.  Then 
with  a  thin  jeweler's  file,  cut  them  flat  from  labial  to  lingual. 
Do  not  cut  the  full  depth  of  the  decay  in  the  dentin,  but  only 
the  depth  of  the  enamel.  That  can  be  filed  away  without  arous- 
ing sensitiveness,  and,  when  necessary,  may  be  done  a  little  at 


Fig.    177. 


KlG.    17 


an,l   figure' n8\I.c-Iin^ial';icw:"'"  '""'■^"'  ---■''-'"^ -"-«'■"■    l^is-   '"T  Siv-  (!„-  IuI.kU  vi.w 
26b 


Fio.    179. 


Fig.   180. 


Figs.  179.  180.  Caries  of  the  deciduous  incisors  of  such  moderate  degn"ee  as  to  permit  of  treat- 
ment by  cutting,  followed  by  the  use  of  silver  nitrate.  Figure  179  is  the  labial  view  and  Figure  180 
the  lingual  view. 


Fin.   LSI. 


if 


J. 


Fig.   182. 


Tigs.  l.sl.  1S2.  Tlie  samo  .as  Figures  ITn.  l.sd  .aftpr  filing  awa.v  some  of  tlio  proximal  surfaces 
anil  treatment  of  tlie  an-as  of  (lera>- with  sil\er  ii'tiato.  I'igure  isl,  labial  \ie\v.  Figure  IS'i,  lingual 
view. 

26c 


MANAGEMENT    OF    CHILDREN'S    TEETH.  249 

a  time  on  different  days.  Leave  the  decayed  material  in  the 
dentin  where  it  is.  Do  not  disturb  it  or  attempt  to  remove  it. 
The  removal  of  this  is  particularly  painful  to  the  child.  Cut 
away  the  angle  of  the  tooth  and  follow  straight  toward  the  gingi- 
val, leaving  the  surface  flat,  being  careful  to  incline  the  file  so 
as  to  cut  most  from  the  lingual  surface,  making  a  V-shaped 
opening  as  shown  in  Figures  181,  182.  In  making  these  cuts, 
it  is  best  to  note  carefully  the  position  of  the  gum  septum,  and, 
if  possible,  avoid  cutting  so  far  that  the  gum  tissue  will  over- 
lap the  cut  surface;  for  this  will  often  make  a  little  pocket  in 
which  it  will  be  difficult  to  prevent  decay  starting  afresh.  The 
little  fellows,  unless  there  is  something  that  hurts  to  prevent 
them,  are  good  feeders  and  will  bite  through  foodstuffs  enough 
to  keep  these  spaces  pretty  well  cleaned  and  it  is  now  easy  to 
supplement  the  natural  by  artificial  cleaning.  When  these  have 
been  cut  in  this  way  and  finished  with  polishing  tape  or  the 
disk,  if  some  decay  is  left  or  some  dentin  is  exposed,  it  should 
be  treated  with  silver  nitrate.  To  do  this,  first  lay  a  crystal  of 
silver  nitrate  on  a  glass  slab  and  crush  it.  Have  some  water 
and  an  orangewood  stick  cut  to  a  point  ready  (an  ordinary 
wooden  toothpick  with  a  flat  end  may  be  used).  Put  a  single 
small  drop  of  water  on  the  crushed  crystal  and  make  as  nearly 
a  saturated  solution  as  possible.  Slip  the  rubber  dam  over  the 
teeth,  hold  it  with  the  fingers  of  the  left  hand,  dry  the  cut  sur- 
faces and  apply  this  solution  to  the  cut  surface  and  the  decay 
m  the  dentin  until  it  is  well  saturated.  Now,  if  it  is  possible 
to  place  the  cut  surfaces  directly  in  the  sunlight  for  ten  minutes, 
do  so.  The  mirror  can  be  used  to  reflect  the  sun's  rays  directly 
onto  the  cut  surface.  If  the  direct  rays  of  the  sun  can  not  be 
had,  use  the  brightest  light  available,  and,  if  possible,  continue 
it  longer.  If  time  enough  can  not  be  given  at  a  first  trial  to 
obtain  a  full  black  color  of  the  carious  dentin,  try  again  at 
another  sitting  and  another  until  it  is  obtained.  Generally, 
after  one  or  two  sittings,  the  child  will  learn  just  what  is 
wanted  and  plenty  of  time  can  be  given.  Each  carious  area, 
such  as  shown  in  the  illustrations,  should  be  treated  in  the  same 
way. 

The  object  in  this  treatment  is  to  fill  the  part  of  the  dentin 
softened  by  decay  with  the  insoluble  salt  of  silver  that  has 
been  precipitated  by  light,  and  incidentally  to  destroy  the  organ- 
isms in  it.  That  portion  of  silver  nitrate,  which  has  not  been 
precipitated  by  light,  dissolves  out  within  a  short  time  and  is 
gone ;  it  is  of  no  value.    It  is  useless  to  endeavor  to  treat  such 


250  PATHOLOGY    OF    THE    HAED    TISSUES   OF    THE    TEETH. 

decays  with  silver  nitrate  without  this  exposure  to  light.  But 
when  the  full  black  color  is  obtained,  decay  is  generally  effec- 
tually stopped.  To  do  this  requires  such  control  of  the  child 
as  will  enable  one  to  use  the  file  a  little  at  a  time  and  succeed  in 
shaping  the  surfaces  and  in  polishing  them.  This  may  be  done 
with  a  thin  stone  in  the  engine  and  finished  with  disks.  In  this 
work  the  child  need  not  be  troubled  with  the  rubber  dam  or  any 
close  confinement.  But  in  applying  silver  nitrate,  the  rubber  dam 
should  be  used.  Applications  made  without  it  will  generally  be 
useless.  One  should  make  no  attempt  to  tie  on  the  rubber  dam. 
Indeed,  nothing  should  be  done  that  is  likely  to  cause  pain. 
When  this  has  been  held  in  position  for  ten  minutes,  or  longer, 
if  the  child  is  not  too  restless,  throw  a  stream  of  water  on  it 
to  wash  away  superfluous  silver  nitrate  and  end  the  sitting  for 
the  day.  When  it  is  apparent  that  the  first  application  is 
ineffective,  make  another  after  one  or  two  days.  Repeat  this 
as  often  as  may  be  necessary.  All  exposed  dentin  and  the  decay 
should  assume  a  full  black  color.  Sound  enamel  will  not  be 
stained.  Any  silver  nitrate  precipitated  on  the  surface  of  the 
enamel  will  disappear  within  a  few  days. 

Generally  decay  is  effectually  stopped  by  this  treatment 
if  the  teeth  and  cut  surfaces  are  kept  fairly  well  cleaned.  The 
cleaning  may  be  done  by  the  mother  or  the  nurse  after  proper 
instruction.  The  dentist,  however,  should  see  these  cases  fre- 
quently to  know  that  the  cleaning  is  well  done.  He  may  find  it 
necessary  to  repeat  the  treatment  with  silver  nitrate  occasion- 
ally. Sometimes  we  find  caries  of  the  enamel  beginning  in  the 
gingival  thirds  of  the  labial  surfaces.  If  these  can  be  discov- 
ered before  the  enamel  rods  have  fallen  out,  they  may  be  cleaned, 
using  caution  not  to  break  away  the  frail  enamel,  and  treated 
with  silver  nitrate  without  further  preparation.  Then  the  clean- 
ing with  the  brush  should  be  effective. 

Either  this  incipient  decay  of  the  enamel  or  the  deeper 
decays  of  the  proximal  surfaces  will  be  stopped,  provided  the 
surface  is  such  that  it  can  be  kept  fairly  clean.  In  this  treat- 
ment one  will  escape  most  of  the  painful  part  of  the  operation 
in  the  treatment  of  these  cases,  for  the  little  filing  that  is  to  be 
done  will  generally  not  be  very  painful.  This  is  applicable  to 
the  proximal  surfaces  of  incisors  and  cuspids  and  to  labial 
cavities.  The  labial  cavities,  from  which  enamel  rods  have 
fallen,  can  not  be  cut  away  very  completely,  but  we  can  break 
away  the  enamel  and  trim  it  carefully  so  as  to  make  these  depres- 
sions as  smooth  as  possible  and  then  treat  them  in  the  same 


MANAGEMENT    OF    CHILDREN'S    TEETH.  251 

way,  and,  by  proper  instructions  to  parents,  they  may  be  kept 
clean  by  brushing,  and  the  teeth,  although  mutilated  and  out  of 
shape,  will  be  useful  to  the  time  of  their  shedding.  All  cases 
treated  in  this  way  should  be  carefully  watched,  and  if  any  sign 
of  the  recurrence  of  decay  is  noted,  the  silver  nitrate  should 
again  be  applied. 

A  word  of  caution  should  be  said  about  the  use  of  silver 
nitrate,  and  it  is  an  important  one.  It  must  not  be  used  if  the 
decay  has  approached  near  the  pulp  of  the  tooth.  There  is 
nothing  else  that  will  cause  so  severe  a  toothache  as  silver  nitrate 
used  over  a  pulp  that  is  nearly  exposed  by  decay.  Personally, 
I  have  had  a  few  very  memorable  experiences  with  it.  The  pain 
was  so  severe  and  so  uncontrollable  that  I  felt  compelled  to 
sacrifice  important  teeth.  One  may  use  silver  nitrate  with  per- 
fect freedom  wherever  there  is  a  good  coating  of  sound  dentin 
over  the  pulp,  but  we  must  not  risk  affecting  the  pulp.  Of  course, 
up  to  a  certain  age  we  have  the  recourse  of  destroying  the  pulp 
and  removing  it,  but  after  the  beginning  of  the  absorption  of 
the  roots  that  recourse  is  lost  to  us.  Treatment  with  silver 
nitrate  should  be  confined  strictly  to  shallow  cavities.  It  is  not 
well  suited  to  deep  cavities  in  which  there  will  be  accumulation. 
Its  success  depends  much  upon  strict  cleanliness  and  free  wash- 
ings by  the  fluids  of  the  mouth  and  by  foodstuffs  after  the 
treatment.  Other  plans  of  treatment  must  be  employed  for 
deeper  cavities.  The  application  of  the  silver  nitrate  seems 
to  be  of  much  benefit  also  in  beginning  caries  of  enamel.  When 
it  has  been  precipitated  freely  among  the  loosened  ends  of  the 
enamel  rods,  decay  does  not  rebegin  so  readily  and  such  vigorous 
cleaning  is  not  necessary  to  hold  it  in  check. 

A  word  as  to  the  handling  of  children  in  this  class  of  cases. 
A  dental  school  clinic  is  not  a  suitable  place  to  handle  little 
children.  We  are  practically  debarred  by  the  conditions  from 
teaching  this  clinically  in  schools.  If  I  am  to  handle  children, 
I  want  to  know  the  parents ;  I  want  to  know  that  they  are 
depending  on  me  to  manage  the  teeth  of  their  children  and  that 
I  will  have  their  assistance  and  sympathy  in  this  management. 
I  will  not  undertake,  further  than  for  present  relief,  the  handling 
of  children  of  strangers,  and  I  would  not  advise  anyone  to  try  to 
do  it.  Remember  that  in  undertaking  to  treat  decay  of  these 
teeth,  it  is  a  thing  that  one  must  begin  to-day  and  follow  it  up 
from  week  to  week  and  from  year  to  year,  until  the  shedding 
time  of  these  teeth,  and  one  should  have  that  particularly  in  view 
and  have  the  parents  particularly  impressed  with  this  necessity. 


252  PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE   TEETH. 

Of  course,  we  can  not  expect  much  assistance  from  the  child, 
as  the  rule.  Yet,  many  of  them  become  enthusiastic  and  do 
their  part  most  bravely.  Furthermore,  the  prophylactic  work 
with  the  tooth  brush  must  be  done  by  the  parent  or  the  nurse, 
and  this  should  be  insisted  upon,  and  when  we  have  made  a 
silver  nitrate  treatment  we  must  expect  to  have  the  child  brought 
to  us  and  examine  these  teeth  from  time  to  time  and  see  that 
decay  has  not  again  started  and  is  making  inroads.  We  may, 
if  decay  is  again  starting  up  in  some  part  of  a  surface  that  has 
been  treated  in  this  way,  treat  it  again  and  stop  it  again,  and 
again,  if  necessary. 

There  are  some  objections  to  this  method  of  treatment. 
The  first  objection  is  that  it  makes  the  cut  surfaces  of  the  teeth 
very  black,  and  often  this  will  show  through  the  enamel  and 
give  it  a  very  bad  appearance.  This  adds  to  the  disfigurement 
caused  by  the  necessary  cutting.  For  this  reason,  it  is  a  very 
objectionable  practice  from  the  esthetic  standpoint,  and  yet, 
with  all  of  its  objections,  it  is  often  the  best  we  can  do.  Parents 
will  object  to  the  discoloration  of  the  teeth  in  many  cases ;  yet, 
if  the  child  is  very  sensitive,  we  can  scarcely  do  better  than  to. 
use  this  method.  The  teeth  can  be  made  to  look  very  much  better 
by  other  methods  of  treatment,  however,  methods  that  will  be 
more  painful  to  the  child. 

We    may     EXCAVATE    THE     CAVITIES     AND     FILL     WITH     CEMENT, 
hill's    stopping,    OE    base    PLATE    GUTTA-PERCHA.       WhCTC    We    Can 

succeed  in  making  the  necessary  excavation,  this  should  be  pre- 
ferred, but  to  fill  with  these  materials  at  all  successfully,  we 
must  excavate  the  cavities  quite  thoroughly.  In  filling  these 
little  teeth  with  cement,  I  should  not  insist  upon  extensions 
of  the  cavity  —  extensions  for  prevention  —  but  should  simply 
remove  the  decay,  cutting  away  the  overhanging  margins  of 
enamel  and  making  the  filling  without  any  considerable  effort 
at  extension.  Unfortunately,  the  cements  are  not  reliable  and 
in  many  cases  they  will  wash  out  from  these  little  teeth  very 
quickly;  in  some  other  cases  again,  they  seem  to  stand  quite 
well.  Sometimes  cement  fillings,  put  in  early,  stand  until  the 
teeth  are  shed.  But  whenever  fillings  of  this  class  are  used, 
the  child  should  be  seen  frequently  and  the  fillings  renewed  if 
they  waste  away,  or  are  found  to  l)e  very  leaky  from  shrinkage. 
Extensions  of  decay  beside  the  filling  will  also  require  treat- 
ment. We  need  to  watch  these  teeth  much  closer  than  we 
watch  the  teeth  of  older  persons,  for  changes  occur  rapidly; 
the  predisposition  to  decay  is  often  very  severe,  so  that  the 


MANAGEMENT    OF    CHILDREN'S    TEETH.  253 

teeth  decay  very  quickly  indeed,  and,  unless  we  keep  a  very 
close  watch  of  them,  we  will  find  that  they  have  decayed  badly 
in  the  interim.  In  this  connection,  it  is  especially  unfortunate 
that  our  cements  are  so  unreliable.  A  cement  that  we  may  use 
this  week  and  find  afterward  that  it  is  doing  good  service,  may 
not  be  good  next  month.  These  changes  that  occur  in  the 
cements  are  very  vexatious.  No  means  has  yet  been  devised  by 
which  they  can  be  prevented,  but  very  earnest  search  is  being 
made.  Of  course,  wherever  we  can,  a  gold  filling  is  the  right 
thing  to  make,  but  the  cases  where  we  can  make  gold  fillings 
successfully  in  the  teeth  of  little  children  are  very  few.  It 
should  be  undertaken  only  when  we  have  the  most  positive  assur- 
ance that  a  really  good  filling  can  be  made.  Also,  we  must  be 
especially  careful  to  preserve  the  courage  of  the  children. 

THE  TREATMENT  OF  DECAYS  IN   THE  OCCLUSAL  SURFACES  OF 
DECIDUOUS  MOLAR  TEETH. 

In  these  we  should  not  care  particularly  for  the  color,  and 
we  may  use  any  of  the  filling  materials  without  the  color  objec- 
tion that  pertains  in  the  incisors.  If  we  obtain  control  of  the 
child  before  the  decays  are  large,  we  may  break  away  the  enamel 
from  about  the  cavity,  open  it  as  widely  as  possible,  and  then 
use  silver  nitrate,  not,  in  this  case,  entirely  for  the  purpose  of 
stopping  decay,  but  for  the  purpose  of  relieving  the  sensitive- 
ness. For  this  purpose  it  should  be  used  in  almost  precisely 
the  same  manner  that  we  would  for  the  stopping  of  the  carious 
process  in  shallow  cavities.  After  the  action  of  the  silver  nitrate 
for  a  week  or  ten  days,  having  applied  it  two  or  three  times, 
we  will  generally  find  that  the  sensitiveness  has  been  relieved, 
and  then  we  may  cut  out  the  decay  and  make  a  filling.  In  the 
meantime,  especial  care  should  be  taken  in  washing  the  cavities 
clean  after  eating  and  keeping  them  so  that  they  will  be  washed 
freely  with  the  fluids  of  the  mouth.  The  difficulty  with  these 
decays  in  the  occlusal  surfaces  is  that,  unless  we  can  open 
them  very  wide,  they  will  fill  up  with  food  which  will  ferment 
and  the  decay  will  again  progress,  notwithstanding  the  treat- 
ment with  silver  nitrate.  Therefore,  this  treatment  should  be 
mainly  for  the  purpose  of  obtunding  the  sensitiveness  in  order 
that  we  may  excavate  and  make  a  filling.  In  this,  we  are  running 
the  risk  of  considerable  discoloration  of  the  dentin  that  will 
show  through  the  enamel.  We  will  not  always  succeed  well  with 
this  process ;  sometimes  the  sensitiveness  will  remain  and  hinder 
us  from  making  a  sufficient  excavation,  but  the  case  will  be  the 


254  PATHOLOGY    OF    THE    HAKD    TISSUES   OF    THE    TEETH. 

better  for  the  use  of  the  silver  nitrate  in  the  limiting  of  the 
decay  that  will  occur,  even  if  we  do  not  entirely  succeed.  We 
may  repeat  this  again  and  again,  if  the  cavity  is  not  so  large 
as  to  encroach  too  near  the  pulp  of  the  tooth.  When  these  have 
been  excavated,  they  may  be  filled  readily  with  amalgam,  or  with 
gold  in  some  cases.  When  a  case  can  be  handled  sufficiently  well 
to  fill  with  gold,  one  should  not  use  silver  nitrate  and  have  the 
tooth  blackened  about  the  margins  of  the  filling,  but  should 
excavate  and  fill  the  cavity  just  the  same  as  for  an  adult.  There 
is  no  difference  whatever  in  the  operation  except  that  we  have 
the  child  to  deal  with.  Taking  it  all  in  all,  amalgam  seems  to 
be  the  best  material  for  filling  this  class  of  cavities,  though 
oxyphosphate  of  copper  cement  is  often  doing  excellent  service. 

TREATMENT    OF    DECAYS    IN    THE    PROXIMAL    SURFACES    OF    DECmUOUS 

MOLAR    TEETH. 

These  are  difficult  in  the  extreme  to  handle.  The  deciduous 
molars  are  larger  than  the  bicuspids  which  come  in  their  place, 
and  they  are  in  many  cases  considerably  crowded  when  the  per- 
manent incisor  teeth  come  through.  The  deciduous  cuspid  tooth 
is  also  smaller  than  the  tooth  which  will  replace  it.  If  we  cut  the 
proximal  surfaces  of  the  deciduous  molars,  they  usually  fall 
together  very  quickly,  consequently  we  are,  in  a  measure, 
debarred  from  that  method  of  handling  proximal  cavities  in 
them;  and  yet  not  entirely,  for,  if  we  can  treat  these  cavities 
when  they  are  small,  we  may,  by  a  different  method,  cut  them  out 
without  separating  the  teeth  so  far  as  to  be  in  trouble  from  their 
dropping  together.  Generally  we  will  find  these  decays  begin- 
ning pretty  close  to  the  occlusal  portion  of  the  surface,  or  near 
the  marginal  ridge,  and  the  form  of  the  crown  is  such  that  if 
we  slope  the  cut  well  to  the  linguo-gingival,  i.  e.,  slope  our  cutting 
toward  the  gingival  on  the  lingual,  we  may  cut  away  considerably 
without  entirely  destroying  the  contact  of  these  teeth,  or,  if  we  , 
destroy  the  contact,  leave  enough  of  enamel  upon  the  proximal 
surface  toward  the  buccal  so  that  it  will  come  against  the  enamel 
of  the  next  tooth,  making  a  new  contact  that  will  be  good  and 
sufficient.  The  occlusal  surfaces  of  the  deciduous  teeth  are  repre- 
sented somewhat  enlarged  in  Figure  183.  In  Figure  184  they 
are  represented  as  the  proximal  surfaces  should  be  cut  in  this 
treatment.  Generally  decay  has  occurred  in  the  bucco-liiignal 
center  of  the  occlusal  third  of  the  mesial  surface.  We  may  make 
a  cut  in  this  way,  sloping  linguo-gingivally,  and  leave  a  portion 
near  the  buccal  angle  of  the  surface  to  make  a  new  contact.    They 


Fio.   183. 


Flo.  184. 


Fio.  185. 


Fig.  186. 


Fig.   is.?.     Tlip  deciduous  teeth  of  the  k^ft  side  of  the  upper  jaw,  showing  no  caries. 

Fig.  184.  The  same  as  Figure  1S3  after  treatment  of  caries  by  cutting  out  broadly  to  the  lino-ual 
tor  the  partial  removal  of  carious  areas  in  the  proximal  surfaces  'and  treatment  with  silver  nitrate. 
Note  particularly  the  contacts  left  to  the  buccal  of  the  separation. 

Fig.   185.     The  deciduous  teeth  and  the  permanent  first  molar  of  the  ri^ht  side  of  the  upper  jaw. 

Fig.  186.  The  same  as  Figure  185  after  treatment  of  caries  by  cutting  a  V-shaped  opening  to 
the  lingual  for  the  removal,  in  part,  of  proximal  decay  and  treatment  with  silver  nitrate.  This  illus- 
tration includes  the  treatment  of  the  distal  surface  of  the  second  deciduous  molar.  Incidentally  this 
frees  the  broad  mesial  surface  of  the  permanent  first  molar  from  a  broad  area  of  near  approach  "to  the 
second  deciduous  molar. 


MANAGEMENT    OF    CHILDREN'S    TEETH.  255 

will  not  drop  together  sufficiently  to  let  the  cut  surface  make  a 
contact.  The  danger  in  cutting  away  the  proximal  surfaces  of 
the  permanent  teeth  is  that  the  flat  cut  surfaces  are  liable  to 
come  together,  by  the  twisting  of  the  teeth  in  their  sockets,  and 
make  a  flat  contact  that  holds  food  and  debris  which  will  very 
certainly  cause  decay.  If  we  can  cut  the  deciduous  teeth  as 
Dr.  Robert  Arthur  recommended  for  the  permanent  teeth  (which, 
by  the  way,  has  gone  entirely  out  of  use  now  because  the  teeth 
would  drop  together  and  make  flat  contacts),  we  can  hold  the 
deciduous  teeth  in  position  and  keep  the  surfaces  in  a  form  that 
will  be  self-cleaning  until  the  normal  time  of  shedding.  One 
should  be  especially  careful  to  make  cuts  of  such  form  that  food 
going  into  them  will  slide  toward  the  lingual  and  pass  out  in  that 
direction,  and  in  this  way  keep  the  cut  surfaces  continually  clean. 
If  we  cut  these  boldly  apart,  cutting  away  the  entire  proximal 
surfaces,  the  teeth  will  usually  not  come  together  entirely  because 
of  the  wide  spreading  of  the  roots.  In  cases  in  which  I  have  done 
this,  difficulty  is  experienced  from  the  fact  that  there  is  a  broad 
gum  septum  exposed,  and  in  the  act  of  mastication,  food  is  forced 
upon  it  and  it  becomes  so  painful  that  the  child  will  almost  refuse 
to  chew  meats  or  any  food  that  requires  considerable  mastica- 
tion, and  the  teeth  become  almost  useless  if  cut  sufficiently  to 
keep  them  apart,  i.  e.,  if  the  whole  proximal  surfaces  are  cut  away 
so  there  will  be  no  contact.  We  must  always  be  on  our  guard 
about  cutting  too  far,  and  this  treatment  should  be  used  only  in 
cases  in  which  cavities  are  neither  large  nor  deep.  We  may  use 
silver  nitrate  in  these  cases  and  not  cut  out  the  entire  decayed 
area,  just  the  same  as  in  the  incisor  teeth. 

It  will  often  become  necessary  to  treat  the  distal  surface  of 
the  second  deciduous  molar  after  the  first  permanent  molar  has 
taken  its  place,  as  represented  in  Figure  185.  In  that  case,  the 
distal  surface  of  the  temporary  tooth  may  be  cut  as  shown  in 
Figure  186,  but  in  no  case  should  the  mesial  surface  of  the  per- 
manent molar  be  cut  in  this  way.  If  that  tooth  has  a  decay,  every 
step  in  its  treatment  should  be  to  the  end  of  placing  finally  a 
filling  in  perfect  form.  Temporary  expedients  may  be  necessary 
to  gain  the  conditions  for  a  successful  operation,  but  when  these 
conditions  can  be  had,  the  filling  should  be  made. 

Filling  these  proximal  cavities  is  a  difficult  proceeding  on 
account  of  the  sensitiveness  and  on  account  of  the  difficulties  of 
position.  The  teeth  are  generally  strongly  bell  crowned;  the 
gums  usually  come  up  into  the  interproximal  spaces  very  near 
to  the  contact,  even  though  we  find  some  decay ;  it  is  only  after 


256  PATHOLOGY   OF    THE    HAKD    TISSUES   OF    THE    TEETH. 

decay  has  progressed  for  a  considerable  time  and  food  has 
lodged,  that  the  gums  are  out  of  the  way.  One  of  the  difficulties 
of  the  treatment  by  cutting  is  that  we  will  come  upon  the  gums. 

Another  difficulty  is  the  proximity  of  the  pulp  of  the  tooth. 
The  pulps  in  the  deciduous  molars  are  large  and  we  are  liable 
to  encroach  upon  the  pulp  too  closely  if  the  cavities  are  too  large 
to  cut  out  in  the  way  mentioned.  Of  course,  where  we  can  control 
the  child  to  prepare  these  cavities  and  make  fillings,  even  though 
we  can  not  make  much  extension,  it  is  still  the  better  method  to 
make  fillings  rather  than  cut  away  the  surfaces,  and  for  this 
purpose  I  should  say  that  there  is  nothing  better  than  a  good 
amalgam  filling,  if  well  put  in  and  polished  properly  afterward. 
This  matter  of  care  in  putting  in  these  fillings,  however,  is  just 
as  important  as  it  is  in  the  teeth  of  adults.  "We  should  not  neg- 
lect any  detail  because  we  are  handling  a  child,  for,  with  them, 
decay  is  so  much  more  rapid  that  any  little  neglect  of  this  kind 
will  tell  more  quickly  than  it  will  in  the  teeth  of  adults.  The 
polish  should  be  well  made.  If  we  can  handle  a  child  to  put  in 
the  filling,  we  can  at  a  subsequent  sitting  obtain  a  good  polish 
and  then  the  filling  will  be  serviceable. 

Thus  far  it  has  been  presupposed  that  the  children  are 
brought  to  the  dentist  sufficiently  often  that  he  may  be  able  to 
follow  up  the  treatment.  Not  only  this,  but  it  is  supposed  that 
children  have  been  brought  to  the  dentist  early  enough  so  that 
he  has  been  able  to  handle  these  decays  before  they  are  large; 
and,  where  this  is  done,  one  ought  to  succeed  in  the  treatment  of 
these  teeth.  But  the  difficulty  that  confronts  one  in  practice  is 
that  parents  too  often  bring  their  children  after  decay  has  pro- 
gressed so  far  that  toothache  has  already  occurred.  Parents  do 
not  realize  that  decay  is  going  so  far ;  they  may  notice  that  there 
are  decayed  spots  in  the  teeth  and  be  anxious  about  them,  but  at 
the  same  time,  are  likely  to  put  off  all  effort  at  treatment  until 
the  child  has  a  sleepless  night  with  toothache.  The  child  is 
already  tortured  with  pain ;  anything  one  may  do  will  hurt  the 
child  inordinately  and  one  has  the  worst  possible  condition  to 
begin  with.  In  this  case  we  are  reduced  to  the  alternative  of  tem- 
porizing or  immediate  extraction.  The  first  effort  will  be  to 
relieve  pain,  and  for  the  present  nothing  else  should  be  done. 
If  possible,  the  child  should  be  made  comfortable,  and  the  treat- 
ment continued  at  a  subsequent  sitting,  after  the  child  has  slept 
and  recovered  its  composure.  If  the  pulp  is  exposed,  which  will 
generally  be  the  case  when  the  excavation  is  made,  you  may 
destroy  it,  remove  it  and  fill  the  roots,  and  in  this  way  succeed, 


MANAGEMENT    OF    CHILDREN'S    TEETH.  257 

provided  the  absorption  of  the  roots  has  not  begun.  That  must 
be  looked  into  carefully,  but  if  the  child  is  brought  at  an  age 
when  the  absorption  of  the  roots  has  begun,  there  is  practically 
no  alternative  but  to  extract  the  tooth  or  cut  away  the  pulp  by 
the  use  of  cocaine  and  fill  the  remaining  portion  of  the  canal, 
running  the  risk  of  alveolar  abscess.  It  is  generally  best  to 
extract  the  tooth  as  the  alternative,  notwithstanding  the  injury 
that  is  liable  to  result.  We  are  presented  with  conditions  in 
which  we  are  unable  to  do  anything  else,  and  we  should  not  try 
to  do  the  impossible.  Wherever  the  age  of  the  child  will  allow, 
carefully  destroy  these  pulps  and  fill  the  roots,  and  in  this  way 
preserve  the  teeth.  That  operation  has  been  done  sufSciently  to 
fully  test  its  merits,  and  we  know  that  it  is  as  successful  as  it  is 
with  the  teeth  of  the  adult,  provided  we  use  sufficient  caution  as 
to  the  time  at  which  it  is  done. 

It  should  be  remembered  always  that  success  in  the  treat- 
ment of  these  teeth  depends  on  the  same  care  as  the  treatment 
of  the  teeth  of  the  adult.  The  fact  that  they  are  to  serve  only 
for  a  short  time  is  fully  counterbalanced  by  the  other  fact  that  the 
tendency  to  caries  is  much  greater  in  the  child ;  so  that  because 
of  any  little  neglect  in  operating,  decay  will  recur  more  rapidly 
and  the  fillings  will  be  more  quickly  undermined  and  destroyed. 
For  this  reason,  careful  attention  should  be  given  to  every  detail 
of  the  operations  upon  them. 


27 


258  PATHOLOGY   OF   THE   HARD   TISSUES   OF   THE  TEETH. 


THE  CHILDHOOD  PEEIOD  OF  THE  PERMANENT 

TEETH. 

niLUSTRATION :    FIGURE  187. 

The  childhood  period  of  the  permanent  teeth  comprises  the 
time  from  their  first  appearance  through  the  gums  until  the 
growth  of  their  roots  has  been  completed,  exclusive  of  the  third 
molars.  This  includes  the  time  from  about  the  sixth  to  the 
fifteenth  or  sixteenth  year.  During  all  of  this  time  there  will 
constantly  be  some  permanent  teeth  present  in  the  mouth  that 
can  not  be  treated  as  temporary  teeth,  nor  as  we  might  treat  the 
teeth  of  an  adult  under  certain  conditions  brought  about  by 
causes  that  may  be  presented.  The  roots  of  the  permanent  teeth 
are  not  completed  until  some  time  after  they  have  taken  their 
places  in  the  arch.  During  this  time  of  growth  they  are  liable 
to  rapidly  progressive  caries,  the  pulps  are  much  larger  than 
in  adult  life  and  are  therefore  especially  liable  to  become  exposed 
by  caries  or  in  the  preparation  of  cavities.  In  the  event  of 
exposure  we  are  debarred  from  removal  of  the  pulp  and  making 
a  root  filling  in  the  tooth  affected,  up  to  the  particular  time  of 
the  completion  of  the  growth  of  the  root  and  the  narrowing  of 
its  apical  foramen  to  a  very  small  opening.  Therefore,  we  will 
often  be  presented  with  conditions  in  which  exposure  of  the  pulp 
of  the  tooth  by  caries  means  the  loss  of  the  tooth  no  matter  how 
important  it  may  be  to  the  future  of  the  child.  The  period, 
therefore,  includes  the  consideration  of  the  growth  of  the  roots 
of  the  permanent  teeth  and  the  treatment  of  caries  to  which 
they  are  liable.  It  will  be  noticed  that  the  childhood  period  of 
the  deciduous  teeth  overlaps  considerably  the  childhood  period 
of  the  permanent  teeth.  But  these  should  always  be  held  dis- 
tinctly separate  in  the  consideration  and  treatment  of  caries. 
even  though  the  cases  in  each  field  may  occur  simultaneously. 

Growth  op  the  Roots  of  the  Permanent  Teeth. 

Passing  to  the  consideration  of  the  growth  of  the  roots  of 
the  permanent  teeth,  we  will  yet  consider  the  patient  a  child, 
although  he  or  she  may  have  the  adult  teeth. 

The  time  of  the  eruption  of  the  permanent  teeth  is,  normally, 
the  same  as  the  shedding  of  the  deciduous  teeth,  but  it  is  spec- 
ially given  in  the  figures  placed  below  each  tooth  in  Figure  187. 


,     ,,      ^^1  i     "JKigraiiiiiKUic    ifiiiescntatiun    of    the    progress    nf    th(>   calcififution    o(    the   permanent 

teem,  ilip  teetli  of  the  left  side  of  tile  njiper  jaw  are  represented  in  outline.  Below  each  tooth  a 
igure  IS  placed  which  represents  the  siveuige  year  of  the  eruption  of  that  tnoth.  Upon  each  tooth 
figriires  are  placed  at  intervals  representing  the  date,  in  veais.  of  the  progress  of  its  calcification  to  that 
hiiie  I  he  relation  of  the  progress  of  ealciflcatioii  between  the  dilierent  teeth,  or  the  contemporaneous 
calcihcation  lines,  nia.v  be  found  b.v  following  anv  individual  fifnire  from  tooth  to  tooth.  The  figure  7, 
for  insiance.  is  on  the  junction  of  the  middle  and  gingival  thirds  of  the  root  of  the  central  incisor 
and,  reading  from  left  to  right,  it  graduall.v  drops  down  to  a  little  below  midlcngth  ol  the  crown  of 
I  he  second  bicuspid;  it  then  jumps  to  about  half  length  of  the  root  of  the  first  molar:  then  back  to 
Ihe  junction  of  the  occlusal  and  middle  thirds  of  the  crown  of  the  second  molar.  It  does  not  appear 
at  all  on  the  third  molar.  Anv  other  ,>eav  niav  be  followed  in  the  same  wav.  The  first  of  the  two 
hgures  placed  above  each  tooth  represents  a  date  at  which  the  apex  of  the  root  of  that  tooth  has  fre- 
quently been  found  sufficiently  narrowed  to  permit  of  root  tilling.  The  second  figure  represents  the 
date  at  which  the  apex  of  the  root  is  still  occasionally  found  too  widely  open  for  root  fillin"  Kven 
wider  variations  will  sometinies  be  found.  It  must  be  remembered  that'  in  such  a  diagrammatic  rep- 
resentation, only  an  approximation  to  a  general  average  can  be  expected.  Tolerablv  wide  variation" 
from   this  average  will   occur. 


THE    CHILDHOOD    PERIOD    OF    THE    PEKMANENT    TEETH.  259 

The  incisors,  cuspids  and  bicuspids  are  often  called  the  suc- 
cedaneous  teeth,  because  they  take  the  place  of  the  deciduous 
incisors,  cuspids  and  molars.  The  roots  of  the  teeth  are  not 
complete  when  the  crowns  first  present  through  the  gum;  they 
are  only  partially  grown.  That  is  a  general  rule  to  which  there 
are  some  exceptions.  The  exceptions  are  almost  wholly  with 
teeth  that  have  been  delayed  in  erupting  from  the  causes  which 
have  been  mentioned.  Generally  the  root  of  the  tooth  will  be 
completed  somewhere  near  its  normal  time,  even  though  the 
eruption  of  the  tooth  may  be  delayed.  There  are  exceptions, 
however,  to  this  rule.  Sometimes  a  permanent  tooth  is  delayed 
in  its  formation,  so  that  the  delay  is  actually  caused  by  the  later 
development  of  the  tooth.  This  seems  to  occur  to  the  lateral 
incisors  oftener  than  to  other  teeth.  It  is  not  very  uncommon 
to  find  these  one  or  two  years  late.  Occasionally,  but  much  less 
frequently,  a  bicuspid,  or  some  other  tooth,  is  late  in  its  devel- 
opment. Excellent  and  very  reliable  studies  of  this  may  be  made 
when  one  has  learned  to  read  the  signs  correctly,  in  cases  of 
atrophy.  The  atrophy  marks  in  the  enamel  occur  on  the  partic- 
ular part  of  each  tooth  that  was  being  developed  at  the  same 
time.  The  irregularities  in  the  position  of  these  lines  show 
clearly  what  teeth,  if  any,  have  been  late  in  the  development  of 
their  crowns.  Occasionally  a  bicuspid  is  found  to  have  begun 
the  formation  of  its  crown  abnormally  early  and  receives  the 
atrophy  mark  with  the  incisors,  which  is  contrary  to  the  rule. 
It  is  not  very  uncommon  to  find  the  marks  on  the  lateral  incisors, 
showing  that  they  have  been  late  in  their  calcification.  Occa- 
sionally, also,  when  we  find  an  atrophy  mark  near  the  incisal 
edge  of  incisors  and  look  to  the  first  molars,  we  find  the  atrophy 
mark  at  half  length  of  the  crown,  showing  that  these  teeth  had 
begun  their  calcification  at  an  earlier  date  than  normal,  etc. 
This  is  a  condition  that  is  difficult  to  diagnose,  but  occasionally 
we  are  surprised  to  find  the  root  of  a  tooth  not  fully  developed 
at  a  much  later  time  than  the  normal. 

The  first  molar  is  the  slowest  tooth  in  its  development  with 
which  we  have  to  deal.  The  calcification  of  this  tooth  has 
usually  begun  at  birth.  I  have  made  examinations  in  many 
cases  of  still-birth  at  term,  and  in  but  few  have  I  found  a  failure 
of  the  beginning  of  calcification  of  this  tooth.  Yet,  the  tooth 
does  not  erupt  until  the  child  is  six  years  old,  or  during  the 
sixth  year;  the  child  is  generally  nearer  six  and  a  half  years 
old;  occasionally  we  will  see  them  presenting  a  little  before 
the  sixth  year,  but  the  average  is  somewhat  later  than  the  six- 


260  PATHOLOGY    OF    THE    HAED    TISSUES   OF    THE   TEETH. 

year-old  point.  Somewhat  rarely,  much  wider  variations  from 
the  average  time  is  seen.  In  one  case  I  saw  the  first  permanent 
molars  through  the  gums  and  in  occlusion  at  four  years  old. 
Again,  two  little  girls  just  five  years  old,  cousins,  had  the  first 
molars  in  full  occlusion.  Delay  to  seven  and  a  half  and  even 
eight  years  has  been  known,  but  such  delays  are  rare.  The 
roots  of  these  teeth  are  rarely  completed  before  the  tenth  or 
twelfth  year,  giving  four  or  five  years  after  the  eruption  of  the 
crown  for  the  development  of  the  root,  and,  in  many  instances, 
the  length  of  the  root  is  not  complete  until  six  years  after 
eruption.  If  we  extract  these  teeth  before  the  eleventh  or  twelfth 
year  we,  wiU  generally  find  that  the  apical  foramina  have 
not  been  closed  down  to  a  small  opening.  The  important  point 
is  the  relation  of  this  closure  of  the  apical  foramen  to  the 
destruction  and  removal  of  the  pulp  and  the  filling  of  the  roots. 
The  chart,  Figure  187,  represents  the  contemporaneous  calcifi- 
cation lines  in  figures  placed  upon  each  tooth,  a  figure  for  each 
year  during  its  development,  representing  the  progress  of  its 
calcification.  By  following  any  given  figure  from  tooth  to  tooth, 
the  particular  part  of  the  root  developed  at  the  year  represented 
will  be  found.  When  information  is  desired  regarding  any 
particular  tooth,  the  figures  placed  upon  it  give  the  growth 
for  each  year.  The  figures  placed  above  the  roots  of  the  teeth 
give  the  earliest  date  in  the  age  of  the  child  at  which  the  apical 
foramen  of  the  roots  have  frequently  been  found  sufBciently  nar- 
rowed to  permit  of  root  filling  and  the  latest  date  at  which 
they  have  still  been  frequently  found  not  sufficiently  narrowed. 
In  this  the  occasional  cases  of  abnormally  early  teeth  and  abnor- 
mally late  teeth  are  not  included. 

In  considering  the  lengthening  of  the  roots  of  the  teeth, 
we  must  give  about  another  year  after  the  root  has  attained 
properly  its  length  for  the  reduction  of  the  size  of  the  apical 
foramen.  The  length  of  the  root  of  the  first  molar,  coming 
through  at  six  years,  is  sufficiently  complete  at  from  ten  to 
twelve  years ;  that  is,  from  four  to  six  years  after  its  eruption. 
The  central  incisors,  erupting  at  six  or  seven,  will  have  the 
foramen  sufficiently  closed  at  about  nine  to  twelve  years ;  three 
to  five  years  after  eruption.  With  all  of  the  other  teeth,  we  may 
allow  three  to  four  years  after  eruption.  The  lateral  comes 
through  at  eight,  will  be  completed  from  eleven  to  twelve;  the 
first  bicuspid  comes  through  at  ten  and  will  be  completed  at  from 
thirteen  to  fourteen;  the  second  bicuspid  at  very  nearly  the 
same  time.     The  cuspid  will  be  complete  at  about  fifteen  to 


THE    CHILDHOOD    PERIOD    OF    THE    PERMANENT    TEETH.  261 

sixteen,  coming  tbrougli  at  twelve.  I  have  never  seen  a  cuspid 
that  was  not  complete  at  sixteen,  yet  I  know  of  several  cases 
where  they  were  decidedly  incomplete  at  fifteen,  and  they  are 
generally  incomplete  at  fourteen.  We  occasionally  have  condi- 
tions calling  for  the  destruction  of  the  pulp  in  the  second  molar 
before  the  roots  have  been  completed.  I  have  had  a  number 
of  cases  in  which  I  destroyed  the  pulp  of  this  tooth  too  early, 
removed  the  pulp  and  found  broad,  open  apical  foramina  that 
defeated  root  filling.  We  can  not  calculate  certainly  that  this 
tooth  will  be  completed  before  the  person  is  fifteen  to  eighteen 
years  old. 

In  cases  of  delayed  eruption,  we  should  always  be  on  our 
guard  as  to  the  removal  of  pulps.  A  patient  may  present  with 
a  tooth  in  position,  and  without  gaining  a  history  of  the  tooth, 
we  may  not  know  that  it  has  been  delayed  in  eruption  and  be 
unable  to  make  a  root  filling  because  of  the  lack  of  development 
of  the  root.  One  case  came  to  me  a  number  of  years  ago,  where 
a  friend  of  mine  got  into  difficulty,  and  got  me  into  difSculty, 
too,  with  a  patient  of  mine  who  happened  to  be  visiting  him. 
He  found  an  exposed  pulp  in  a  bicuspid,  or  one  that  was  so 
nearly  exposed  that  he  destroyed  it.  He  returned  the  patient 
to  me,  stating  in  a  note  that  he  had  gotten  into  trouble  with  the 
tooth  —  an  abscess  had  formed  that  would  not  heal.  I  found 
he  had  lost  a  pledget  of  cotton  through  a  broad,  open  root  canal. 
I  cut  through  the  tissues  and  removed  the  cotton.  I  cut  off 
considerable  of  the  root  and  filled  it  with  gutta-percha,  but  the 
tooth  was  lost  some  six  months  afterward.  Possibly,  if  the 
circumstances  had  been  known,  that  tooth  might  have  been 
tided  along  for  a  year  or  so  without  destroying  the  pulp,  giving 
opportunity  for  the  apical  foramen  to  be  narrowed  down.  We 
should  be  as  careful  as  possible  not  to  destroy  pulps  before  the 
roots  are  completed. 

It  is  deplorable  to  have  a  patient  present  with  an  exposed 
pulp  in  an  important  tooth,  the  root  of  which  we  know  to  be 
only  partially  developed,  making  it  impossible  to  remove  the 
pulp  and  make  a  serviceable  root  filling.  My  advice  is  not  to 
undertake  to  do  impossible  things.  In  cases  in  which  there  is 
a  possibility  of  the  root  being  sufficiently  developed,  the  effort 
should  be  made  to  treat  it,  but  the  patient  or  the  parents  should 
know  what  may  be  expected,  that  it  will  probably  be  necessary 
to  extract  the  tooth. 


262  PATHOLOGY   OF   THE   HABD   TISSUES   OF   THE   TEETH. 

InTEROXJSPING    of    THE   FlEST    PERMANENT    MOLAES. 

At  the  risk  of  going  somewhat  beyond  the  field  intended  in  this 
book,  I  must  call  attention  to  what  I  will  designate  as  the  proper 
intercusping  of  the  first  permanent  molars  when  they  first  come 
into  occlusion.  The  teeth  are  formed  so  that  the  teeth  of  the  lower 
jaw  will  intercusp  with  the  teeth  of  the  upper  jaw  in  a  certain 
way,  which  is  very  clearly  shown  in  the  photograph.  Figure  101, 
of  this  volume.  Also  the  forms  of  the  teeth  are  such  that  if  they 
miss  the  exact  position  in  which  they  should  occlude  a  little  way 
only,  as  they  come  into  occlusion,  the  tendency  is  to  slide  on  the 
slopes  of  the  cusps  in  such  a  way  as  to  bring  them  to  the  exact 
relative  positions  designed  —  a  most  beautiful  provision  of 
nature  for  correcting  slight  deviations  that  should  be  closely 
studied  until  its  meaning  is  clearly  understood.  When,  however, 
the  teeth  are  so  much  out  of  normal  relation  at  the  time  that 
the  teeth  first  make  contact  in  coming  into  occlusion  that  the 
points  of  the  cusps  overstep  each  other  ever  so  little,  the  wrong 
slopes  become  the  moving  force  directing  them  into  an  increased 
abnormality  of  position.  That  is  to  say,  if  the  mesio-buccal  cusp 
of  the  upper  first  molar  should  strike  the  point  of  the  mesio- 
buccal  cusp  of  the  lower  first  molar  in  such  a  way  that  its  distal 
slope  instead  of  its  mesial  slope  slides  on  that  cusp,  the  upper 
molar  will  be  pushed  to  the  mesial  instead  of  the  distal  and  the 
abnormality  will  be  increased  instead  of  being  corrected.  In 
that  case,  the  upper  first  molar  will  be  one  full  cusp  width  too 
far  forward  in  its  relation  to  the  lower  first  molar.  This  error 
will  then  be  forced  upon  the  other  teeth,  crowding  the  front 
part  of  the  upper  arch  so  that  there  will  be  either  protrusion 
of  the  upper  front  teeth  or  irregularity  among  the  bicuspids 
or  cuspids  as  a  result.  On  the  other  hand,  the  case  may  be 
reversed.  In  the  relation  of  these  teeth  to  each  other  as  they 
approach  in  coming  into  occlusion,  the  lower  first  molar  may 
be  quite  a  little  forward  of  its  normal  relation  to  the  upper, 
but  so  long  as  the  point  of  the  mesial  cusp  of  the  upper  strikes 
ever  so  little  to  the  mesial  of  the  point  of  the  disto-buccal  cusp 
of  the  lower  first  molar,  the  sliding  on  the  slopes  of  the  cusps 
will  correct  the  malposition.  If,  however,  the  position  of  the 
point  of  the  mesio-buccal  cusp  of  the  upper  first  molar  should 
be  ever  so  little  to  the  distal  of  the  point  of  the  disto-buccal 
cusp  of  the  lower  first  molar,  the  sliding  will  increase  the  mal- 
position instead  of  correcting  it.  The  result  will  be  an  irregu- 
larity or  a  protrusion  of  the  lower  teeth.    In  this  the  buccal 


THE   CHILDHOOD   PEKIOD   OF   THE  PEEMANENT   TEETH.         263 

cusps  only  have  been  mentioned  because  these  only  are  shown 
in  the  available  illustration.  The  lingual  cusps,  particularly 
of  the  upper  molars,  play  an  important  part  on  the  same  prin- 
ciple mentioned  for  the  buccal  cusps.  This  error  when  these 
teeth  come  into  occlusion  is  the  basis  of  more  irregularities  of 
the  teeth  than  any  other  one  thing.  The  opportunity  for  this, 
however,  is  usually  foimd  in  caries  of  deciduous  molars  by 
which  they  have  been  lost,  lost  their  crowns,  or  some  part  of 
their  mesio-distal  breadth,  which  allows  one  or  the  other  of  the 
first  molars  to  stray  too  far  from  its  normal  position  in  coming 
into  occlusion  with  its  fellow.  Dentists  having  families  of  chil- 
dren under  their  care  should  discover  this  particular  error  in 
its  inception  and  contrive  means  for  its  correction  at  that  time 
and  prevent  the  impending  irregularity. 

Special,  Functions  of  the  First  Permanent  Molaes. 

The  first  molars  have  special  functions  to  perform.  They 
seem  to  have  been  so  placed  and  timed  in  their  coming  into 
position  for  these  special  purposes.  They  come  into  position, 
occluding  with  each  other,  just  before  the  shedding  of  the  decid- 
uous teeth  begins.  Normally,  the  shedding  process  begins  almost 
immediately  they  come  into  full  occlusion.  The  front  part  of 
the  arch  is  soon  broken  by  the  shedding  of  the  deciduous  teeth 
and  these  four  teeth  stand  in  occlusion,  propping  the  jaws  in 
the  position  they  should  occupy  during  the  shedding  of  the 
deciduous  teeth  and  during  the  reformation  of  the  arch.  They 
hold  the  jaws  firmly  in  the  position  they  should  occupy  during 
the  growth  and  development  of  the  face.  In  the  examination 
of  a  considerable  number  of  cases,  it  is  found  that,  with  the  effect 
of  disease  and  the  irregularities  that  occur  in  the  absorption  of 
the  roots  of  the  deciduous  teeth  and  their  replacement  by  the 
permanent  teeth,  the  support  of  the  jaws  is  many  times  almost 
completely  lost  but  for  the  presence  of  the  first  molars.  They 
do  much  more  than  this.  Accompanying  the  shedding  process 
there  is  a  rapid  growth  of  the  bones  of  the  jaws  and  face,  making 
for  the  changes  of  the  features  from  the  form  in  the  child  and 
the  modeling  of  the  features  of  the  adult.  Particularly  the 
space  from  the  lower  orbital  ridge  to  the  crest  of  the  alveolar 
process  between  the  teeth  is  increasing,  the  depth  of  the  lower 
jaw  from  the  crest  of  the  alveolar  process  to  its  lower  border 
is  increasing.  Together  these  are  lengthening  the  face  from 
above  downward.  At  the  same  time  the  whole  front  of  the 
face  is  being  carried  forward,  increasing  the  distance  from 


264  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE   TEETH. 

the  ear  to  the  front  of  the  mouth,  modeling  out  that  promi- 
nence of  the  features  that  makes  a  large  part  of  the  difference 
in  the  cast  of  the  countenance  between  the  child  and  the  adult. 
It  may  be  said  that  the  deciduous  molars  act  to  support  the 
occlusion  in  the  early  part  of  the  shedding  period,  but  this 
is  readily  shown  to  be  only  in  part  by  the  many  cases  in  which 
the  bite  is  raised  off  from  these  teeth  in  the  progress  of  growth 
of  the  first  molars.  The  models  referred  to  previously,  of  the 
mouth  of  a  boy  almost  fifteen  years  old,  whose  deciduous  molars 
had  not  been  shed  and  had  not  been  lifted  by  the  growth  of  the 
alveolar  processes,  illustrates  such  a  condition.  The  upper 
incisors  and  cuspids  overlap  the  lower  in  position  to  slide  freely 
upon  each  other  and  could  be  no  support  to  the  occlusion.  The 
jaws  are  held  firmly  in  position  by  the  four  powerful  first 
molars.  These,  in  their  usual  movement  in  the  lengthening 
of  the  face,  which  is  clearly  one  of  their  normal  functions,  have 
caused  the  stationary  deciduous  molars  to  be  carried  apart 
about  one-third  of  an  inch  between  their  occlusal  surfaces.  This 
abnormal  case  shows  plainly  the  function  of  the  first  molars, 
not  alone  in  holding  the  jaws  in  their  proper  relative  positions 
while  the  occlusion  is  broken  up  in  the  shedding  process,  but 
that  they  also,  by  their  movement  in  harmony  with  the  general 
growth  of  the  face,  carry  the  jaws  farther  apart  and  in  this  way 
assist  in  the  formation  of  the  features  by  lengthening  the  face. 
When  these  teeth  are  lost  early  by  decay,  which  occurs 
much  too  often,  there  is  apt  to  be  much  distortion  of  the  features 
resulting.  This  is  sufficiently  apparent  from  careful  clinical 
observation,  as  has  been  noted  by  many  men.  From  all  of  these 
sources  of  information  it  seems  certain  that  in  the  general  growth 
that  is  going  on  no  part  is  taken  by  the  deciduous  molars  after 
the  normal  time  of  the  beginning  of  the  absorption  of  their  roots. 
In  most  cases  they  may  be  carried  forward  passively  with  the 
expansion,  or  lengthening  of  the  bite,  but  in  many  it  seems 
clearly  demonstrable  that  their  continued  presence  later  becomes 
a  positive  hindrance  to  development.  In  these  cases  at  least 
the  normal  development  would  not  occur  if  the  first  molars  had 
been  lost.  No  measurements  have  yet  been  made  by  which  the 
particular  directions  of  distortion  and  the  amounts  have  been 
determined.  Apparatus  for  this  work  has  been  constructed,  but 
at  the  time  of  writing  not  enough  work  has  been  done  to  give 
sufficient  basis  for  exact  statements.  When  this  work  has  been 
done,  it  will  probably  furnish  more  exact  information,  and,  in 
view  of  this,  a  lengthy  discussion  of  this  problem  seems  unwise. 


THE    CHILDHOOD    PERIOD    OF    THE    PERMANENT    TEETH.  205 

Further  consideration  in  a  general  way  will  be  given  to  the 
evils  resulting  from  the  early  loss  of  the  first  molars  in  connec- 
tion with  the  consideration  of  caries  of  these  teeth. 

Caries  of  Permanent  Teeth  During  the  Childhood  Period. 

The  first  molars  and  the  incisors  are  particularly  liable  to 
caries  during  the  childhood  period.  The  first  molars  suffer 
much  the  oftenest.  The  fact  that  these  teeth  take  their  places 
very  quietly  to  the  distal  of  the  deciduous  molars  without  the 
dropping  away  of  any  of  the  deciduous  teeth  to  announce  their 
coming,  serves  to  conceal  their  eruption.  Parents  generally  do 
not  know  of  the  presence  of  these  teeth,  or  do  not  realize  that 
they  are  permanent  teeth.  They  are,  therefore,  more  frequently 
neglected  than  any  other  teeth. 

First  permanent  molars.  The  lower  first  molars  are  usually 
the  first  of  the  permanent  teeth  to  be  attacked  by  caries.  The 
decay  is  almost  always  in  the  central  pit  of  the  occlusal  surface, 
but  occasionally  in  the  buccal  pit  also.  Cavities  in  a  similar 
position  in  the  upper  first  molars  begin  soon  afterward.  This 
is  so  common  and  the  effects  of  this  early  beginning  of  decay 
in  these  teeth  are  so  grave,  that  it  requires  special  consideration. 
These  teeth  are  the  first  of  the  permanent  teeth  erupted  and  are 
usually  through  the  gums  by  the  middle  of  the  sixth  year  of  the 
child's  life.  In  this,  however,  there  are  pretty  wide  variations 
which  have  been  noted.  They  are  often  deeply  decayed  by  the 
eighth  year  and  generally  require  fillings  by  that  time  in  fami- 
lies in  whom  there  is  considerable  susceptibility  to  caries.  There 
are  no  other  teeth  that  are  so  often  lost  from  inattention  at  the 
proper  time  as  these.  There  are  no  other  teeth  easier  to  protect 
by  proper  attention  correctly  timed.  The  early  loss  of  the  first 
molars  is  from  occlusal  decays  in  about  ninety-five  per  cent  of 
cases,  and  these  are  the  easiest  cavities  to  manage  when  taken 
in  time.  They  are  also  the  most  important  of  the  molar  teeth. 
They  are  the  largest,  strongest  and  most  effective  in  mastica- 
tion. For  several  reasons,  which  have  been  given  above,  their 
loss  causes  more  derangement  of  the  masticatory  apparatus 
and  of  facial  expression  than  any  other,  not  even  excepting  the 
incisors,  for  these  have  not  so  prominent  a  function  in  the  gen- 
eral development.  If  these  latter  are  lost  early  or  late,  the  loss 
is  replaced  artificially.  The  form  of  the  face  and  the  expression, 
which  would  otherwise  be  marred  by  shrinkage  to  fill  the  space, 
is  prevented ;  and  mastication  is  not  seriously  deranged.    How- 


266  PATHOLOGY   OF   THK   HAED   TISSUES   OF   THE   TEETH. 

ever,  when  the  first  molars  are  lost,  the  damage  is  practically 
irreparable.  The  occlusion  of  the  remaining  teeth  is  necessarily 
deranged  by  the  falling  backward  of  the  bicuspids  and  the  move- 
ment forward  of  the  remaining  molars.  When  they  are  removed 
as  early  as  the  ninth  or  tenth  year,  the  space  of  the  first  molars 
will  be  closed  by  these  movements  of  the  teeth  and  the  occlusion 
will  be  better  than  if  lost  later,  but  the  normal  prominence  of 
the  front  teeth  and  lips  will  be  wanting,  which  is  a  permanent 
injury  to  the  expression  of  the  face.  The  occlusion  will  be  imper- 
fect at  best;  in  many  cases  it  will  be  very  defective,  for  often 
the  molar  teeth  assume  such  an  inclination  to  the  mesial  that 
the  occlusal  surfaces  do  not  meet  fairly  together  but  strike  only 
upon  the  distal  cusps,  rendering  mastication  imperfect.  If  one 
only  is  lost,  the  incisor  teeth  are  generally  crowded  to  that  side 
in  the  filling  of  the  lost  space,  moving  away  from  the  median 
line  and  seriously  deranging  the  expression  of  the  mouth.  When 
two  are  lost  on  the  same  side,  the  teeth  occupying  the  front 
of  the  mouth  generally  will  be  thrown  to  that  side.  Both  theo- 
retically and  practically,  it  seems  best,  when  one  must  be  lost, 
to  extract  all  four  to  obtain  greater  regularity  of  the  features. 
Few  operators,  however,  have  the  moral  courage  to  sacrifice  two 
or  three  good  teeth  for  a  possible  gain  in  occlusion  and  expres- 
sion in  the  somewhat  remote  future. 

The  time  at  which  first  molars  are  lost  is  important.  They 
are  the  first  of  the  permanent  teeth.  They  are  placed  to  the 
distal  of  the  deciduous  set.  When  they  have  taken  their  places 
and  the  upper  and  lower  teeth  have  occluded  with  each  other, 
the  shedding  of  the  deciduous  teeth  begins.  The  first  molars 
hold  the  jaws  in  position  and  preserve  the  symmetry  of  the  face 
while  the  deciduous  teeth  are  being  shed  and  replaced  by  the 
permanent  ones.  The  second  molars  are  not  erupted  until  the 
twelfth  year,  and  by  this  time  the  shedding  and  replacement 
of  the  teeth  have  been  nearly  completed;  therefore,  in  case 
these  teeth  are  lost  before  the  deciduous  teeth  are  replaced  by 
the  permanent  ones,  the  face  is  apt  to  be  shortened  because  of 
the  lack  of  support  for  the  lower  jaw,  the  normal  movement 
of  the  front  of  the  mouth  forward  is  diminished  and  derange- 
ments in  the  occlusion  occur.  All  of  these  considerations  demand 
that  these  toeth  be  protected;  yet  children  are  brought  to  us 
continually  with  their  teeth  decayed  beyond  all  hope  of  repair, 
and  they  must  be  removed  as  the  lesser  of  two  evils.  In  many 
cases  in  which  permanent  repair  is  impossible,  the  teeth  may 
receive  such  treatment  as  to  render  them  comfortable  and  use- 


THE   CHILDHOOD   PERIOD   OF   THE  PERMANENT   TEETH.         267 

ful  temporarily.  Under  these  circumstances,  tlie  operator  is 
able  to  choose  the  time  for  their  removal.  On  this  point  there 
is  much  difference  of  opinion,  but  most  careful  observers  agree 
that  the  best  arrangement  of  the  features  and  the  remaining 
teeth  will  be  obtained  when  they  are  removed  some  time  before 
the  eruption  of  the  second  molars,  or  about  the  ninth  to  the 
tenth  year.  My  own  observation  corroborates  this  opinion. 
At  this  time  enough  of  the  teeth  in  the  front  of  the  mouth  will 
be  in  position  to  give  the  occlusion  considerable  support;  the 
second  molars,  in  erupting,  will  come  forward  nearly  into  the 
position  of  the  lost  first  molars;  somewhat  less  flattening  of 
the  face  will  occur  than  when  they  are  removed  earlier;  the 
surfaces  of  the  second  molars  will  usually  be  in  better  occlusion 
and  the  interproximal  contacts  will  be  much  better  than  when 
these  teeth  are  removed  later.  My  own  observations,  however, 
do  not  lead  me  to  the  opinion  that,  when  there  is  no  longer  a  hope 
for  their  permanent  retention,  there  is  a  material  gain  in  wait- 
ing to  the  ninth  year  that  compensates  for  the  dangers  of  suf- 
fering and  discouragement  to  the  patient  in  the  treatment  of 
these  teeth  in  cases  that  promise  much  difficulty  and  pain.  There- 
fore, in  many  of  the  cases  presented,  I  should  remove  them  at 
once  as  the  lesser  of  two  evils.  It  is  especially  desirable  at  this 
time  that  the  little  patients  be  not  troubled  with  teeth  that  are 
frequently  sore  and  interfering  with  the  free  use  of  the  teeth 
in  the  mastication  of  food.  To  have  a  child  in  a  condition  of 
inability  to  masticate  food  in  comfort  for  a  considerable  time 
because  teeth  are  sore,  establishes  a  habit  of  bolting  food  that 
is  very  damaging  to  the  physical  development  of  the  person. 

In  the  consideration  of  the  question  of  permanent  retention 
of  these  teeth,  the  superficial  area  of  the  decay  is  of  secondary 
importance.  The  depth  of  the  decay,  its  relation  to  the  pulp  of 
the  tooth,  and  the  condition  of  the  pulp,  are  the  important  ques- 
tions. In  adults,  if  the  pulp  of  the  tooth  becomes  involved,  we 
may  remove  it  and  retain  the  tooth  in  serviceable  condition.  With 
the  first  molars  in  patients  eight  or  nine  years  old  we  are 
debarred,  and  under  twelve  years  old  we  are  likely  to  be  debarred 
from  root-filling  because  the  apical  foramina  have  not  been  nar- 
rowed by  the  completion  of  the  growth  of  the  roots.  Really  root- 
filling  is  decidedly  unsafe  before  the  fourteenth  or  fifteenth  year. 
Even  when  done  at  from  fourteen  to  sixteen  my  observation  leads 
me  to  the  conclusion  that  most  of  these  teeth  with  root  fillings 
are  lost  before  the  person  is  thirty  years  old.  Therefore,  if  the 
pulp  has  become  hopelessly  involved,  the  tooth  will  be  lost  and 


268  PATHOLOGY    OF   THE    HABD    TISSUES    OF    THE    TEETH. 

may  as  well  be  extracted  at  once.  To  retain  the  tooth  for  a  few- 
years,  or  even  eight  or  ten,  is  bad  management. 

These  considerations  should  lead  to  the  utmost  care  in  the 
management  of  these  teeth.  Whenever  possible,  cavities  occur- 
ring in  pits  or  fissures  should  be  filled  early  —  before  consider- 
able progress  has  been  made  —  and  should,  if  the  self-control 
and  physical  condition  of  the  child  wiU  permit,  be  filled  perma- 
nently with  gold.  It  is  only  necessary  to  uncover  the  decayed 
area,  form  the  cavity  with  solid  parallel  walls,  and  follow  out 
sharp  grooves  to  good  finishing  points,  no  other  extension  being 
needed.  The  enamel  in  the  neighborhood  of  these  carious  areas 
is  not  subject  to  decay  because  of  the  friction  of  mastication; 
therefore,  a  good  filling  once  made  is  permanent.  As  I  have  been 
doing  this  generally  for  many  years  and  noting  results  carefully, 
I  feel  free  to  say  that  the  only  question  is  in  being  able  to  make  a 
good  filling.  Amalgam  can  be  substituted  for  gold,  but  at  this 
age  of  the  patient  the  greatest  degree  of  susceptibility  is  present, 
and  this  demands  the  best  of  material  and  the  most  careful 
operating,  and  gold  is  the  safer  material. 

In  deep  cavities  involving  considerable  dentin,  especially  if 
unusually  sensitive,  no  attempt  should  be  made  to  both  excavate 
and  fill  at  the  same  sitting  for  children  under  ten  years  old.  In 
the  first  place,  this  is  likely  to  be  too  much  for  the  endurance  and 
self-control  of  the  child ;  and,  second,  thermal  sensitiveness  being 
somewhat  aroused  by  the  carious  process,  hyperemia  of  the  pulp 
might  readily  be  precipitated  by  completing  the  operation  at  one 
sitting.  The  better  way  is  to  make  a  temporary  filling  of  red  base- 
plate gutta-percha.  The  walls  of  the  cavity  should  be  well  dried 
with  absorbent  cotton  (no  hot-air  drying  should  be  used)  and 
moistened  with  eucalyptol  to  secure  the  cohesion  of  the  gutta- 
percha. By  this  plan  a  perfectly  tight  filling  can  be  made.  The 
case  may  then  be  dismissed  for  twenty  or  thirty  days.  In  that 
time  the  sensitiveness  will  be  diminished  and  the  danger  of  hyper- 
emia of  the  pulp  materially  reduced,  and,  if  the  child  is  under 
good  control,  the  permanent  filling  may  be  inserted.  I  would 
caution  operators,  however,  about  allowing  gutta-percha  fillings 
in  these  teeth  to  go  for  a  longer  time.  Generally  children  who 
have  not  been  forced  into  caution  by  the  presence  of  highly  sensi- 
tive cavities  are  vigorous  chewers  of  food  and  will  wear  out 
gutta-percha  fillings  rapidly.  "Whenever  there  are  reasons  for 
longer  delay  the  gutta-percha  filling  should  be  inspected  and,  if 
necessary,  renewed. 

Often  in  these  cases,  if  cavities  are  not  deep,  there  will  be  a 


THE   CHILDHOOD   PEKIOD   OF   THE   PERMANENT   TEETH.         269 

rapid  improvement  in  the  condition  of  sensitiveness,  if  the  over- 
hanging enamel  is  well  removed,  so  as  to  give  full,  free  admission 
of  the  fluids  of  the  mouth  to  the  cavity.  These  will  dissolve  out 
much  of  the  acid  and  other  irritating  substances  from  the  decay- 
ing mass,  diminish  their  concentration  and  reduce  the  irritation 
to  the  dentinal  fibrils,  partially  removing  the  cause  which  has 
aroused  the  hypersensitiveness.  In  many  cases,  those  in  which 
decay  has  not  approached  near  the  pulp,  the  saturation  of  the 
softened  mass  with  a  solution  of  silver  nitrate  and  exposing  it 
to  a  bright  light  until  it  becomes  black  is  very  effective.  In  this 
case  the  cavity  may  be  left  open  for  a  month  or  more.  The  risk 
of  some  blackening  of  the  dentin  by  the  silver  nitrate  is  justifiable 
if  by  this  means  it  becomes  possible  to  make  a  good  filling.  This 
remedy  should  never  be  used  in  deep  cavities,  because  of  the 
liability  to  produce  intense  pain. 

In  cases  in  which  hyperemia  of  the  pulp  has  occurred  and 
there  have  been  paroxysms  of  pain  at  frequent  intervals,  a  thor- 
ough excavation  of  the  cavity  should  be  made.  This  may,  if  the 
sensitiveness  of  the  tooth  and  the  condition  of  the  child  require, 
be  divided  into  several  sittings,  using  an  antiseptic  and  filling 
with  gutta-percha  for  protection  during  the  intervals.  The  exca- 
vation must  finally  be  made  complete,  however,  in  every  case, 
removing  every  particle  of  softened  dentin  before  any  attempt  at 
permanent  filling  is  made.  It  should  be  determined  definitely 
whether  or  not  caries  has  actually  reached  the  pulp.  If  it  has 
not,  the  case  may  safely  be  regarded  as  simple  hyperemia,  and 
even  though  there  may  have  been  very  severe  paroxysms  of  pain, 
the  chances  are  favorable  for  recovery  by  simply  keeping  the 
cavity  well  filled  with  gutta-percha  for  several  weeks  or  months. 
It  is  difiScult  to  prevent  children  hurting  these  teeth  by  tempera- 
ture changes.  Parents  should  be  instructed  to  withhold  hot  and 
cold  foods  and  drinks,  and,  if  the  weather  is  cold,  to  keep  them 
well  housed  or  especially  guarded  against  breathing  cold  air 
through  the  mouth  when  out  of  doors. 

In  the  above  we  have  considered  only  those  forms  of  treat- 
ment looking  to  the  early  permanent  filling  of  the  first  molars 
with  gold.  Many  cases  will  occur  in  which  this  will  not  be  the 
wisest  course  because  of  our  inability  to  carry  out  the  treatment 
successfully.  In  these  it  is  best  to  use  temporary  fillings  of  such 
a  nature  as  to  give  considerable  time.  These  may  be  made  of 
oxyphosphate  of  copper,  of  Hill's  stopping,  or  of  amalgam,  with 
the  understanding  that  they  are  expected  to  serve  a  temporary 
purpose  only,  awaiting  the  opportunity  to  make  permanent  fill- 
ings. 


270  PATHOLOGY   OF    THE    HAED    TISSUES    OF    THE    TEETH. 

Accidental  exposure  of  the  pulp  while  excavating,  if  done 
according  to  rules  given  in  technical  procedures  in  filling  teeth, 
while  adding  another  serious  complication,  does  not  greatly  add 
to  the  danger.  After  the  application  of  "1-2-3,"  or  oil  of  cloves, 
the  exposure  should  be  capped  with  oxyphosphate  of  zinc.  To 
make  a  successful  capping,  it  is  required  that  all  decayed  mate- 
rial be  removed  from  the  cavity.  Then  take  a  bit  of  ordinary 
writing-paper  and  cut  a  piece  that  will  cover  the  exposure  and 
overlap  well  in  every  direction,  or  in  this  class  of  cavities  it  should 
cover  the  whole  pulpal  wall  and  fit  fairly  well.  Be  sure  that 
everything  is  in  perfect  readiness,  the  rubber  dam  in  place  and 
the  cavity  dry.  Having  tried  the  prepared  paper  and  found  it 
of  proper  size,  flood  the  cavity  with  oil  of  cloves,  "1-2-3"  or 
other  equally  non-irritating  antiseptic.  Then  prepare  some  oxy- 
phosphate of  zinc,  mix  it  rather  thin  and  spatulate  well,  continu- 
ing the  spatulation  until  stiffening  is  just  beginning,  so  that  a 
globule  may  be  held  on  the  bit  of  prepared  paper.  At  this  moment 
dry  out  the  cavity  and  at  once  introduce  the  paper  with  the 
globule  of  cement  directed  toward  the  exposure  and  very  gently 
tap  it  into  position  so  as  to  spread  the  cement  over  the  whole  of 
the  pulpal  wall  of  the  cavity  and  cover  the  exposure  without 
unnecessary  pressure.  Leave  this  without  disturbance  of  any 
kind  for  fifteen  or  twenty  minutes,  or  until  assured  that  the 
cement  is  well  stiffened.  Then  place  a  good  gutta-percha  filling 
over  it  and  allow  this  to  remain  for  one  month.  If  this  has  done 
well,  reinforce  the  cement  covering  by  an  additional  layer,  before 
making  a  permanent  filling. 

Success  in  capping  pulps  depends,  first,  upon  the  selection 
of  suitable  cases,  and,  second,  upon  the  accuracy  of  every  detail 
in  carrying  out  the  procedure.  The  best  cases  are  those  in  which 
the  exposure  has  been  made  in  cutting  hard  dentin  with  a  broad 
blade,  such  as  the  20-9-12  spoon,  which  will  not  drop  into  the  pulp 
chamber  and  lacerate  the  pulp.  If  the  pulp  has  been  exposed 
while  cutting  with  a  bur,  debris  from  the  blades  is  apt  to  be 
forced  into  the  pulp  tissue.  This  makes  the  condition  very  bad. 
If  the  pulp  is  found  exposed,  and  by  this  is  not  meant  fully  open 
to  the  saliva,  but  contact  of  carious  material  with  the  pulp,  the 
case  is  of  the  gravest  character.  The  pulp  will  certainly  be 
infected  and  inflamed,  whether  there  has  or  has  not  been  parox- 
ysms of  pain,  and  with  any  treatment,  over  fifty  per  cent  of  the' 
cases  will  be  lost.  In  children,  however,  a  suflScient  minority  of 
cases  recover  to  demand  that  the  effort  be  made  in  the  more 
favorable  cases.     Much  tinkering  in  the  treatment  should  be 


THE    CHILDHOOD    PERIOD    OP    THE   PERMANENT   TEETH.  271 

avoided.  If  the  case  does  not  do  well  after  one  or  two  straight- 
forward efforts,  abandon  it  without  further  worry  to  the  child. 
In  this  class  of  cases  every  failure,  or  rather  every  period  of 
hyperemic  excitement,  diminishes  the  chances  of  recovery  and 
adds  materially  to  the  difficulty  of  controlling  the  child.  The 
treatment  giving  me  the  greatest  percentage  of  success  has  been 
given  above.  Sometimes,  a  second  effort  will  succeed  when  the 
first  has  failed,  but  a  third  is  not  advisable. 

When  these  cavities  are  presented  to  us  in  patients  fifteen 
years  old,  or  over,  they  present  no  more  of  difficulty  than  other 
pit  cavities.  Other  teeth  are  not  so  often  deeply  decayed  so  early 
after  presenting  through  the  gums  and  do  not  demand  attention 
when  the  child  is  so  young.  They  are,  therefore,  not  so  fre- 
quently neglected,  and  when  they  do  occur,  the  increased  self- 
control  of  the  patient  makes  the  treatment  easier  and  more  cer- 
tain. Decay  involving  the  loss  of  the  pulp  in  any  tooth  before 
the  completion  of  the  roots,  involves  the  loss  of  the  tooth  for  the 
reason  that  root  fillings  can  not  be  successfully  made.  This  fact 
should  be  ever  present  in  the  mind  of  the  practitioner,  and  the 
time  of  the  completion  of  the  roots  of  the  individual  teeth  as  per- 
fectly known  as  their  variations  will  allow. 

It  not  infrequently  happens  that  the  mesial  surface  of  the 
first  molar  begins  to  decay  while  still  in  contact  with  the  second 
deciduous  molar,  and  this  will  be  the  first  proximal  cavity.  In 
children  of  good  self-control  and  endurance,  these  should  be  pre- 
pared and  filled  with  gold  when  discovered,  even  as  ealrly  as  the 
eighth  year.  In  the  reverse  conditions  in  which  the  teeth  are 
excessively  sensitive  and  the  child  very  difficult  to  control,  it  is 
better  to  use  gutta-percha,  zinc  phosphate  or  copper  phosphate 
temporarily,  await  the  shedding  of  the  deciduous  molar  and  seize 
the  opportunity  when  the  whole  proximal  surface  is  exposed  to 
view  to  make  the  permanent  filling.  The  operator  must  not  be 
tempted  by  these  favorable  conditions  into  making  this  a  simple 
cavity  without  due  extension  for  prevention  or  without  cutting 
the  full  retention  seat  in  the  occlusal  surface.  He  must  form  the 
proximal  surface  and  contact  point  to  meet  with  the  second  bicus- 
pid, which  will  be  quickly  in  position.  A  principal  point  in  the 
treatment  will  be  to  determine  what  will  be  the  area  of  liability 
when  the  bicuspid  is  in  position  and  include  it  in  the  area  of  the 
filling.  Failure  in  either  of  these  directions  will  be  fatal  to  the 
future  of  the  filling.  If  existing  conditions  will  not  allow  these 
things  to  be  very  well  done,  it  is  better  to  use  temporary  expedi- 
ents and  await  better  opportunity  for  making  permanent  fillings. 


272  PATHOLOGY    OF    THE    HAKD    TISSUES    OF    THE   TEETH. 

All  that  I  have  said  as  to  the  management  of  the  child,  conditions 
of  sensitiveness  of  dentin,  of  thermal  sensitiveness,  of  pulp  expo- 
sure and  of  the  time  of  extracting  when  that  is  necessary,  while 
speaking  of  occlusal  cavities  in  these  teeth,  applies  here. 

Lingual  pits  of  upper  lateral  incisors,  rarely  in  the  centrals 
also,  are  the  only  other  pit  decays  that  are  found  at  so  early  an 
age.  These  are  not  nearly  so  frequent  as  decays  in  the  first 
molars,  and,  as  a  rule,  occur  somewhat  later.  Occasionally,  how- 
ever, these  are  found  soon  after  these  teeth  are  in  position ;  and 
while  the  gums  still  overlap  the  enamel  so  much  that  it  is  very 
difficult  to  get  the  rubber  dam  placed  without  inflicting  con- 
siderable pain.  Nothing  can  be  done  without  the  dam,  and  this 
is  often  the  most  serious  difficulty  met  with  in  these  cases.  The 
best  plan  is  to  say  to  the  child:  "This  will  hurt  for  a  few  min- 
utes," force  the  ligature  or  special  root  clamp  to  position,  being 
careful  to  be  successful  at  the  first  effort,  and  hold  it  until  the 
pain  has  abated.  If  a  ligature  is  used,  it  must  not  be  forced  on 
the  labial  also  and  drawn  tightly,  as  that  will  cause  unnecessary 
pain  and  do  injury  by  cutting  the  gums  from  the  proximal  sur- 
face of  the  tooth.  Personally,  I  very  much  prefer  to  hold  the 
dam  in  position  with  a  special  instrument  in  the  left  hand  while 
making  the  filling  with  the  right  than  to  use  either  ligature  or 
clamp.  But  in  these  cases  the  special  root  clamps  used  in  treat- 
ing and  filling  crownless  roots  will  do  good  service.  When  the 
cavities  have  not  made  much  progress,  the  actual  excavation  and 
filling  present  no  great  difficulty.  Usually  these  are  not  so  sen- 
sitive as  the  pit  cavities  in  the  first  molars ;  they  are  less  in  area 
and  the  excavation  and  filling  are  more  quickly  done.  Whenever 
the  endurance  of  the  child  will  possibly  permit,  these  cavities 
should  be  excavated  and  filled  permanently  with  gold  at  one  sit- 
ting. The  difficulty  in  placing  the  rubber  dam  seems  to  demand 
this.  When  patients  are  older  and  these  teeth  have  protruded 
through  the  gums  sufficiently  to  render  the  placing  of  the  dam 
reasonably  easy,  they  give  but  little  difficulty.  This  cavity  is, 
however,  likely  to  approach  the  pulp  closely  where  not  appar- 
ently very  deep,  and  especial  care  must  be  exercised,  a  matter 
that  has  been  emphasized. 

Proximal  cavities  in  the  inoisob  teeth  may  occur  as  early 
as  the  eighth  year  in  children  of  very  susceptible  families,  but  it 
is  seldom  that  we  detect  them  so  early.  When  they  do  occur,  they 
are  difficult  of  management,  mainly  on  account  of  the  tender  age 
of  the  patient  and  the  comparatively  long  period  of  sharp  sus- 
ceptibility which  generally  must  follow.    Often  the  crowns  of  the 


THE    CHILDHOOD    PEEIOD    OF    THE    PERMANENT    TEETH.  273 

teeth  are  still  as  much  as  one-third  covered  with  gum  tissue, 
making  the  adjustment  of  the  rubber  dam  especially  difficult  and 
painful.  No  kind  of  filling,  temporary  or  permanent,  can  be 
properly  done  without  it.  When  the  rubber  dam  can  be  held  on 
the  teeth  by  the  contact  points  aided  by  bits  of  cotton,  gutta- 
percha or  cement,  the  difficulty  of  forcing  the  rubber  dam  down 
by  ligatures  will  be  averted.  In  these  cases  it  is  especially  desir- 
able to  use  a  quick-setting  cement,  and,  while  holding  the  rubber 
well  down  on  the  lingual  and  labial,  stick  a  globule  on  the  tooth 
and  hold  it  until  it  stiffens  enough  to  hold  the  dam  in  place. 

The  requirement  is  that  cavities  be  cut  very  wide  toward  the 
labio-gingival  and  linguo-gingival  angles  of  the  proximal  surface 
so  as  to  include  the  whole  area  of  liability,  or  that  extension  for 
prevention  be  carried  to  its  full  limit  and  the  prepared  cavity 
solidly  filled  with  gold.  By  this  it  is  not  meant  that  the  cavity 
shall  be  cut  over  onto  the  labial  surface  so  as  to  show  much  gold, 
but  only  so  far  toward  the  angle  of  the  tooth  as  to  relieve  the 
margin  of  the  filling  from  near  contact  with  the  proximating 
tooth.  Extension  for  prevention  does  not  call  for  the  cutting  of 
proximal  cavities  of  incisors  over  onto  the  labial  surface  in  any 
case,  and  this  should  never  be  done  except  when  demanded  by 
the  extension  of  actual  decay  of  the  dentin  and  baclcward  decay 
of  the  enamel.  Whenever  the  condition  of  the  patient  as  to  cour- 
age and  endurance  will  warrant  this  procedure,  it  should  be  done 
without  hesitation  or  delay.  Clinical  results  mark  this  course  as 
being  at  once  safe  and  reliable  and  so  markedly  the  best  as  to 
speak  most  positively  against  the  opinion  so  often  expressed 
against  using  metallic  fillings  in  the  teeth  of  young  children.  The 
reason  that  these  so  commonly  fail  is  that  they  are  so  commonly 
not  well  done ;  the  extension  for  prevention  is  not  carried  out, 
nor  is  the  filling  well  placed,  the  reasons  being  mainly  that  the 
difficulties  are  not  overcome.  Such  operating  is  useless  under 
these  conditions  and  had  better  not  be  attempted.  In  any  case 
of  this  nature,  in  which  the  operator  can  not  see  his  way  to  carry 
out  extension  for  prevention  to  the  full  limit  and  make  a  perfect 
filling,  he  will  do  better  to  fill  temporarily  with  gutta-percha,  or 
Hill's  stopping,  after  making  the  best  excavation  the  conditions 
will  allow  at  the  time  and  await  better  conditions.  The  tem- 
porary fillings  must  be  carefully  watched,  and  redone  frequently, 
the  patient  encouraged  in  every  way,  and,  at  the  first  oppor- 
tunity for  successful  work,  the  permanent  fillings  should  be  made. 

In  excavating,  it  should  be  especially  remembered  that  at 
this  time  the  pulp  of  the  tooth  is  much  larger  than  in  the  adult, 

28 


274  FATHOLOGY   OF    THE    HAED    TISSUES    OF    THE   TEETH. 

and  the  danger  of  its  exposure  correspondingly  greater.  Also 
that  the  roots  of  the  teeth  are  still  incomplete,  making  the 
removal  of  the  pulp  and  root  filling  out  of  the  question.  The 
pulp  of  the  tooth  must  be  saved  alive  or  the  tooth  will  be  lost. 
These  considerations  call  for  the  most  extreme  care  in  every 
detail.  Broad  cavities  are  no  bar  to  successful  treatment.  The 
pulps  of  these  teeth  are  in  less  danger  from  thermal  sensitive- 
ness and  hyperemia  than  in  adult  teeth.  Depth  of  decay  is  most 
to  be  feared.  The  wide-open  apical  foramen  gives  less  danger 
from  strangulation  of  the  blood  vessels,  and  the  pulps  possess  a 
greater  power  of  recuperation.  When  exposed,  they  give  a  much 
larger  percentage  of  success  in  capping.  The  further  growth  of 
dentin  which  is  still  fairly  active  on  the  wall  of  the  pulp  chamber 
soon  covers  over  such  an  exposure  with  dentin  —  if  capping  is 
successful  —  making  the  cure  complete  and  permanent.  Still,  it 
will  be  the  general  rule  even  with  these,  that  pulps  once  fully 
exposed  by  decay  will  be  lost.  The  rule  that  the  courage  and 
endurance  of  the  child  should  not  be  broken  down  by  any  effort 
at  conservative  treatment  holds  in  these  cases,  as  in  all  others, 
notwithstanding  the  importance  of  the  teeth  under  consideration. 

Proximal  surface  decays,  if  lateral  incisors,  occur  less  fre- 
quently than  similar  decays  in  the  central  incisors  at  so  early 
an  age  as  eight  or  nine  years.  But  cavities  in  these  this  early,  or 
correspondingly  soon  after  their  eruption  when  they  are  late  in 
their  development,  often  present  greater  difficulty  because  of  the 
smallness  of  the  teeth.  The  fact  that  they  frequently  overlap 
the  central  incisors  labially  often  causes  broad  cavities  to  occur 
in  their  mesial  surfaces.  It  is  depth  of  decay,  however,  that  is 
most  to  be  feared.  In  the  management  of  very  early  decays  in 
these  teeth,  it  is  especially  important  that  the  history  as  to  the 
time  of  their  eruption,  as  compared  with  the  centrals,  should  be 
learned.  The  pulps  of  these  teeth  are  very  large  as  compared 
with  the  size  of  the  teeth  soon  after  eruption,  but  grow  smaller 
quite  rapidly.  One  or  two  years  makes  considerable  difference 
as  to  the  danger  of  pulp  exposure  in  cutting  to  a  given  depth,  and 
this  is  the  important  consideration  in  these  early  decays.  The 
irregularity  in  the  time  of  the  development  of  the  lateral  incisors 
gives  an  uncertainty  to  their  treatment  that  does  not  attach  to 
the  centrals,  and  greater  caution  is  necessary. 

Fortunately,  not  very  many  cases  are  met  with  in  which  any 
of  the  incisors  are  found  decayed  in  persons  so  young  as  eight 
or  nine  years.  But  a  few  will  be  presented  in  every  considerable 
practice,  scattering  along  from  eight  to  fourteen.    All  of  these 


THE    CHILDHOOD    PERIOD    OF    THE    PERMANENT    TEETH.  275 

must  be  regarded  as  children  and  treated  accordingly.  But  the 
greater  number  of  these  cavities  will  be  found  in  persons  from 
fifteen  to  eighteen  years  old.  These  patients  will  have  more  self- 
control.  The  teeth  are  through  the  gums  sufEciently  so  that  the 
rubber  dam  and  the  separator  can  be  applied  without  imusual 
pain  and  the  conditions  for  operating  are  in  every  way  improved. 
There  are  not  often  found  in  the  general  conditions  sufficient  rea- 
sons for  temporary  treatment.  At  this  age,  the  patient  will  gen- 
erally not  have  contracted  mincing  habits  of  mastication,  unless 
caused  by  the  interference  of  neglected  decay  of  the  deciduous 
teeth,  and  malleting  will  be  reasonably  well  borne.  It  should  be 
remembered,  however,  that  our  civilized  habits  of  using  the  knife 
and  fork  for  dividing  our  food  and  passing  it  into  the  mouth,  robs 
our  front  teeth  of  their  legitimate  function  of  dividing  the  food 
to  such  a  degree  that  their  peridental  membranes  are  not  propor- 
tionately as  strong  as  those  of  the  back  teeth.  Also  that  the 
direction  of  force  required  in  condensing  gold  is  generally  more 
or  less  across  the  axial  line  of  the  tooth,  and  not  so  well  borne 
for  that  reason.  Greater  care  is  therefore  necessary  in  the  use 
of  force.  Still,  most  of  these  teeth  will  readily  bear  the  full  fif- 
teen pounds  mallet  pressure  required  in  condensing  the  gold, 
when  necessary,  if  carefully  applied  from  the  beginning. 

Open  apical  ends  of  root  canals  of  the  teeth  during  the 
childhood  period  is  always  a  special  menace  in  these  operations, 
because  root  fillings  can  not  be  made  in  cases  in  which  pulps  are 
found  exposed  or  are  exposed  by  any  accident  in  operating.  This 
should  be  ever  present  in  the  mind  of  the  dentist  who  attends  to 
the  teeth  of  children.  It  is  as  much  his  duty  to  use  his  influence 
in  obtaining  the  opportunity  of  watching  these  children  in  order 
that  he  may  do  the  required  operations  in  good  time,  as  it  is  to 
do  the  operations  well.  It  is  not  always  an  easy  matter  to  con- 
vince parents  that  everything  possible  has  been  done  when  they 
bring  in  the  child  with  a  widely  exposed  pulp  at  eight  or  nine 
years  old  and  are  told  that  the  tooth  will  probably  be  lost  in  spite 
of  all  the  dentist  can  do.  A  few  months  earlier  a  safe  operation 
could  have  been  made  had  the  opportunity  been  given.  This 
education  is  best  and  its  effect  is  better  when  given  by  the  dentist 
in  his  office  directly  to  the  parents.  The  pulps  are  being  removed 
from  these  teeth  and  root  fillings  made  much  earlier  than  they 
should  be  in  hundreds  of  cases,  with  the  result  that  abscesses 
occur  under  conditions  at  the  root  apices  which  make  them  incur- 
able. This  happens  oftener  with  the  upper  lateral  incisor  than 
with  the  central.    It  is  not  very  uncommon  for  the  upper  lateral 


276  PATHOLOGY    OF    THE    HABD    TISSUES    OF    THE    TEETH. 

incisors  to  be  one  or  two  years  late  in  their  development.  They 
are  often  much  later  than  any  other  teeth,  except  the  third 
molars,  and  are  in  correspondingly  greater  danger.  Usually 
when  these  teeth  are  much  late  in  coming  into  place  in  the  arch  — 
one  or  two  years  later  than  the  central  incisors  —  they  will  be 
correspondingly  late  in  the  completion  of  the  growth  of  the  roots. 
In  the  great  surgical  clinic  of  Northwestern  University  Dental 
School,  it  has  been  particularly  noted  that  a  majority  of  the  cases 
of  alveolar  abscess,  or  caries  of  bone,  occurring  in  the  upper  jaw, 
arise  from  the  lateral  incisors. 

The  pulps  in  the  latekal  incisors  are  large  compared  with 
the  size  of  the  teeth  during  the  childhood  period  and  for  some 
time  later.  Therefore,  they  are  oftener  exposed  by  decay  occur- 
ring soon  after  their  eruption,  and  by  accident  in  operating,  than 
other  teeth.  For  these  reasons  proportionately  more  of  these 
teeth  require  root  fillings  early  than  other  teeth.  Because  of 
their  frequent  later  development,  frequent  irregular  forms  of 
their  roots  and  also  the  frequent  malposition  to  the  labial,  root 
fillings  in  these  teeth  are  more  difiBcult  and  are  much  more  fre- 
quently made  before  the  apical  foramina  have  been  narrowed 
down  to  small  openings.  For  these  reasons  taken  together,  root 
fillings  are  more  often  imperfect  in  these  than  in  the  other  front 
teeth.  These  are  sufficient  reasons  for  more  frequent  alveolar 
abscesses  and  their  sequellae.  Their  prominent  position  causes 
them  to  be  retained,  notwithstanding  these  adverse  conditions. 

There  is  now  an  unfortunate  tendency  among  dentists  to 
remove  the  pulps  of  teeth  for  very  slight  causes.  This  has  been 
brought  about,  apparently,  by  the  freedom  with  which  healthy 
pulps  are  removed  from  teeth  for  the  purpose  of  forming  abut- 
ments for  bridges.  Much  of  this  is  necessary,  but  much  of  it 
is  bad  practice,  and  especially  the  effect  of  it  is  bad  for  the  reason 
that  it  leads  men  to  place  much  too  low  an  estimate  on  the  value 
of  the  dental  pulp.  Too  many  pulps  are  destroyed  when  other 
means  would  in  the  long  run  be  better,  and  especially  for  young 
people.  The  value  of  a  dental  pulp  should  always  be  reckoned 
in  inverse  ratio  to  the  age  of  the  patient  up  to  the  age  of  twenty- 
five  years.  During  the  childhood  period  of  the  permanent  teeth, 
the  value  of  the  pulp  is  equal  to  the  value  of  the  tooth.  That  is 
to  say,  if  the  pulp  is  lost  before  the  apical  foramen  is  well  nar- 
rowed, the  tooth  will  be  lost.  Of  those  root  fillings  made  for 
patients  between  fifteen  and  sixteen  years  old  which  have  proven 
successful  for  three  months,  more  abscesses  will  occur  later  than 
among  those  in  which  root  fillings  are  made  for  patients  between 


THE    CHILDHOOD    PERIOD    OF    THE   PERMANENT    TEETH.  277 

sixteen  and  seventeen.  More  of  these  latter  will  abscess  than  of 
those  filled  between  seventeen  and  eighteen.  This  will  continue 
progressively  to  patients  who  are  about  twenty-five  or  twenty- 
seven  years  old.  Those  root  fillings  made  between  the  ages  of 
twenty-five  to  twenty-seven,  and  forty  years  will  give  the  longest 
average  of  service.  After  that  age,  there  begins  to  be  more  fre- 
quent interference  with  successful  root  filling  in  the  way  of  calci- 
fications, extreme  narrowing  of  root  canals,  etc.,  that  renders  the 
average  endurance  less  certain.  A  strict  account  of  root  filling 
with  its  results  in  the  endurance  of  the  teeth  without  abscess  will 
give  results  closely  along  these  lines.  Particularly  the  great 
loss  of  teeth  from  abscess  when  root  fillings  are  made  before 
persons  are  twenty  years  old,  should  warn  us  strongly  to  use 
every  reasonable  effort  to  avoid  destroying  pulps  for  young  peo- 
ple. We  must  destroy  pulps  and  make  root  fillings  in  the  incisor 
teeth,  as  the  least  of  two  evils,  when  there  is  no  hope  of  saving 
exposed  pulps  alive.  The  reduction  of  these  cases  of  necessity 
can  come  only  through  greater  care  in  gaining  the  opportunity 
to  attend  more  closely  to  the  care  of  the  teeth  of  our  people  and 
make  necessary  operations  earlier  in  the  progress  of  caries.  This 
means  a  better  education  of  our  people  to  the  necessities  of 
greater  watchfulness  over  the  teeth  of  the  young. 


GLOSSARY  OF  TECHNICAL  TERMS  AND  PHRASES,  WITH  NOTES 


Abrasion.  Wear  of  the  surfaces  of  the  teeth  as  a  result  of  their  use  in  mastica- 
tion. The  condition  to  which  the  term  is  applied  is  usually  a  wear  of  abnormal 
amount  which  does  not  represent  a  corresponding  abnormal  use,  the  excessive  wear 
being  due  to  some  unknown  influence. 

Abscess.     A  cavity  containing  pus. 

Abscess,  alveolae.     See  Alveolar  Abscess. 

Abscess,  lateral.    See  Lateral  Abscess. 

Absorb.     To  suck  up,  to  take  in,  to  remove  by  an  absorbent. 

Absorbent.  An  agent  that  takes  up  moisture.  A  specially  prepared  cotton  — 
absorbent  cotton,  spunk,  or  bibulous  paper,  for  drying  cavities  in  teeth. 

Absorption.  The  act  of  sucking  in ;  removal  by  sucking  in,  or  taking  up.  The 
process  by  which  the  roots  of  the  deciduous  teeth  are  removed.  The  process  by 
which  the  alveolar  process  is  removed  after  the  extraction  of  teeth,  etc.  Absorp- 
tions play  an  important  part  in  the  processes  of  life,  animal  and  vegetable. 

Accretion.  Addition  by  growth,  or  by  deposit,  little  by  little;  may  be  either 
amorphous,  i.  e.,  leaving  no  lines  showing  the  form  of  growth;  or  stratified,  showing 
lines  of  increase.  The  enamel  of  the  teeth  when  reduced  to  microscopic  sections  in 
certain  directions  shows  accretion  lines  or  layers  of  added  material.  See  Lines  of 
Accretion. 

Accretion  lines.    See  Lines  of  Accretion. 

Adhesion.  The  union  of  substances  tliat  differ  in  their  nature,  as:  adhesion 
of  glue  to  wood,  paste  to  paper,  etc.    To  unite  bodies  by  their  surfaces. 

Aeteb  condensation.  Such  condensation  of  the  surface  of  a  filling  as  may  be 
made  after  the  filling  has  been  otherwise  completed. 

Alveolar  abscess.  An  abscess  located  in  the  apical  space,  or  within  the  tissue 
of  the  peridental  membrane  immediately  surrounding  the  apex  of  the  root  of  a  tooth. 
Alveolar  abscess  is  a  distinct  form  of  abscess  occurring  only  after  the  death  of  the 
pulp  of  the  tooth,  and  is  a  result  of  infection  through  the  apical  foramen.  This 
should  be  distinguished  sharply  from  lateral  alveolar  abscess  which  occurs  on  the 
side  of  the  root,  not  involving  the  apical  space  and  in  which  the  pulp  of  the  tooth 
may  be  alive. 

Alveolar  process.  The  projection  of  the  maxillary  bones  which  envelops  the 
roots  of  the  teeth,  and  in  which  their  alveoli  are  formed. 

Alveolus.  (PI.  Alveoli).  A  socket:  The  cavity  in  the  process  of  the  maxil- 
lary bone  in  which  the  root  of  a  tooth  is  fixed. 

Amalgam.  A  metal,  a  mixture,  or  an  alloy  of  t«o  or  more  metals,  comminuted 
and  made  into  a  mass  by  rubbing  with,  and  in  this  manner,  combining  with  mercury. 

Amorphous.  A,  without;  morphous,  form.  A  substance  which  has  no  form  ele- 
ments, or  apparently  has  no  form  elements.  A  substance  that  is  apparently  amor- 
phous to  the  naked  eye  may  show  form  elements  under  the  microscope. 

Anchorage.     The  points  of  fixation  of  fillings  or  artificial  crowns  or  bridges. 

Anesthetic.    A  drug  capable  of  producing  insensibility  to  pain. 

Angle.  The  line,  or  point,  where  two  or  more  surfaces  of  the  teeth  or  walls  of 
cavities  join.  The  mesial  and  buccal  surfaces  join  in  the  formation  of  the  mesio- 
buccal  angle;    a  line  angle.     The  mesial,  buccal  and  occlusal  surfaces  join  in  the 


280  PATHOLOGY    OF    THE    HAKD   TISSUES   OF    THE   TEETH. 

formation  of  the  mesio-bucco-ocelusal  angle;  a  point  angle.  The  so-called  angles 
of  the  teeth  are  generally  smoothly  rounded  but  are  named  as  if  they  were  definite 
angles. 

Note:  The  compound  words  formed  from  the  adjectives  ending  in  al,  as  buccal,  labial,  lingual, 
mesial,  distal,  gingival,  axial,  pulpal,  occlusal,  incisal,  proximal,  have  in  recent  years  assumed  large 
proportions  in  usage  in  dental  nomenclature  because  of  their  convenience  in  the  accurate  designation 
of  angles  of  the  teeth,  margins  and  angles  of  surfaces  of  teeth,  of  naming  complex  cavities,  cavity 
walla,  cavity  angles,  directions  on  surfaces  of  teeth,  etc..  also  in  the  adverbial  forms  ending  in  ly ; 
as  mesially,  distally,  etc.,  in  compounds  or  in  the  simple  fonns,  for  indicating  directions  on,  or  in 
the  teeth,  or  any  directions  in  the  mouth.  In  the  use  of  these,  hundreds  of  combinations  have  been 
employed,  any  of  which  can  be  used  without  confusion  if  used  intelligently.  This  only  requires  care 
as  to  confusing  with  each  other  angles  of  teeth,  angles  of  surfaces  of  teeth,  angles  of  cavities  in 
teeth  and  other  similar  things.  At  present  there  seems  to  be  no  need  for  the  use  of  very  many 
of  these  compound  forms,  but  it  is  by  no  means  certain  that  the  time  has  come  for  forming  rules 
for  the  limitation  of  their  use.  Something  more  than  two-thirds  of  them  are  repetitions  of  the 
same  meaning  by  changing  the  fonn  of  the  compound,  as:  mesio-buccal  and  bucco-mesial  angle  of 
a  tooth ;  such  changes  in  the  relation  of  the  words  give  no  change  whatever  in  ttie  angles  named. 
Again,  in  naming  the  point  angles  of  cavities,  axio-mesio-gingival  angle  may  also  be  written:  axio- 
gingivo -mesial,  mesio-axio-gingival,  mesio-gingivo-axial,  gingivo-mesio- axial  or  gingivo-axio-mesial. 
These  varying  fonns  each  mean  the  same  thing  precisely  and  any  one  of  them  expresses  the  thought 
as  perfectly  as  any  other.  The  use  of  any  one  of  them  instead  of  any  other  one  gives  rise  to  no 
confusion  whatever.  A  few  very  simple  rules  would  cut  off  nearly  all  of  this  class  of  multiplication 
of  compound  forms.  But  I  have  always  felt  that  this  would  place  an  additional  tax  on  the  student 
in  learning  the  use  of  compound  terms.  I  have,  therefore,  waited  for  custom,  or  ideas  of  euphony, 
to  suggest  a  method  of  doing  this.  This  book  has  been  written  without  any  effort  in  this  direction. 
The  rules  in  ray  mind  may,  however,  be  suggested  here,  but  are  given  only  as  suggestions. 

1.  Whenever  axial  occurs,   it  should  be  placed   first  in  the  compound. 

2.  Wherever  pulpal  occurs  in  the  absence  of  axial,   it  should  be  placed  first. 

3.  Wherever  mesial  or  distal  occurs  in  the  absence  of  axial  or  pulpal,  the  one  occurring  should 
come  first  in  the  compound. 

4.  Wherever  the  three- syllable  words,   gingival    or   occlusal,    occur,    they    should   be  placed   last. 
As  simple  as  these  rules  are,  they  would  be  a  considerable  tax  on  the  student  in  the  beginning 

of  his  use  of  compound  terms,  but  there  is  no  doubt  but  that  with  this  restriction,  the  use  of  these 
terms  would  finally  become  easier. 

Until  recently  I  had  supposed  that  the  use  of  the  adverbs  of  direction  had  been  suggested  first 
in  dentistry,  but  it  now  seems  that  the  botanists  have  the  priority.  The  use  made  of  them  in  botany 
is  not  essentially  different.  The  adverbs  of  direction  may  he  used  freely  as  single  words  or  in 
compound  forms  in  which  the  last  word  only  takes  the  ly,  as  raesio- distally ;  from  mesial  to  distal, 
or  mesio-lingually ;     a  diagonal  direction  from  mesial  to  lingual  across  or  through  a  tooth,  etc. 

Generally  but  few  of  these  compound  words  are  used  in  any  one  cavity  description,  and  they  are 
in  no  way  burdensome  after  one  becomes  accustomed  to  their  use.  They  are  the  only  terms  in  which 
cavities  can  be  sufficiently  described,  or  in  which  cavity  preparation  can  be  eflBciently  taught.  There 
is  often  a  tendency  to  the  multiplication  of  these  terms  noticed  among  students  by  naming  unes- 
sential parts  of  cavities,  such  as  naming  individually  every  cavo-surface  line  and  point  angle  of  a 
cavity ;  as  bucco-occlusal  cavo-surface  angle,  bucco-mesial  cavo-surface  angle,  bucco-mesio-occlusal 
cavo-surface  angle,  etc.  This  is  well  enough  as  an  exercise,  but  is  a  waste  of  energy  in  any  essential 
cavity  description.  There  has  been  no  effort  to  include  all  of  these  compound  terms  in  this  glossary; 
only  a  few  of  the  most  essential  are  given. 

Angles  op  cavities  ;  rules  foe  naming.  See  Rules  for  Naming  Angles  of 
('avities.     See  also  names  of  angles  of  cavities. 

Angles  op  shanks  of  instruments.  Named  according  to  number  and  direction 
of  angles,  as  monangle,  binangle,  triple-angle,  contra-angle,  etc. 

Angles  of  surfaces  of  teeth.  Each  surface  of  a  tooth  has  four  angles.  The 
angles  of  the  occlusal  surfaces  of  the  bicuspids  and  molars  are,  the  mesio-buccal, 
disto-buccal,  mesio-lingual  and  the  disto-lingual.  The  angles  of  the  buccal  and 
lingual  surfaces  are,  the  mesio-occlusal,  disto-occlusal,  mesio-gingival  and  disto- 
gingival.  The  angles  of  the  mesial  and  distal  surfaces  are,  the  bucco-occlusal, 
linguo-occlusal,  bucco-gingival  and  linguo-gingival.  The  angles  of  the  labial  and 
lingual  surfaces  of  the  incisors  are,  the  mesio-incisal,  disto-incisal,  mesio-gingival 
and  disto-gingival. 

On  account  of  the  triangular  form  of  mesial  and  distal  surfaces  of  the  incisors, 
these  have  btit  three  angles;  the  labio-gingival,  linguo-gingival  and  incisal  angle. 
The  incisal  angle  named  here  is  an  exception  to  the  rules  in  that  it  is  named  in  a 
single  term.  It  is  formed  by  the  junction  of  the  labial  and  lingual  surfaces  at  the 
incisal  edge.  See  Angles  of  Teeth,  and  note  carefully  the  difference  between  angles 
of  teeth  and  angles  of  surfaces  of  teeth. 

Angles  op  teeth.  The  angles  of  the  teeth  are  named  as  if  the  tooth  were 
cubes,  no  matter  how  irregular  or  how  much  the  angles  may  be  rounded.  In  naming 
tho  angles  of  the  teeth,  compounds  of  the  names  of  the  surfaces  are  used.  There 
are  three  sets  of  angles  named.     The  first   set  is   formed  by   the  junction  of   the 


GLOSSARY    OF    TECHNICAL,   TERMS   AND   PHRASES.  281 

axial  surfaces  with  each  other.  These  form  line  angles  which  reach  from  the  occlusal 
surface  to  the  gingival  line.  They  are  the  mesio-buccal,  disto-buccal,  inesio-lingual 
auil  disto-lingual  angles.  The  second  set  are  also  line  angles,  and  are  formed  by 
the  junetiou  of  the  axial  surfaces  with  the  occlusal  surface.  They  are  the  mesio- 
occlusal,  bucco-occlusal,  disto-occlusal  and  linguo-oeclusal  angles.  The  third  set  are 
point  angles,  formed  by  the  junction  of  three  walls  at  a  point.  They  are  the  mesio- 
bucco-occlusal,  mesio-linguo-occlusal,  disto-bucco-occlusal  and  disto-lingiuj-occlusal. 

The  angles  of  the  incisors  and  cuspids  are:  First  set,  mesio-labial,  disto-labial, 
mesio-lingual  and  disto-lingual  angles.  The  incisal  edge  of  the  incisors  and  cuspids 
has  normally  neither  the  second  nor  third  set  of  angles  complete  in  such  form  as  to 
require  names,  except  the  mesio-incisal  and  disto-incisal  angles.  See  Angles  of  Sur- 
faces of  Teeth. 

Anneal.  To  soften  by  heat  as  in  annealing  a  metal  plate,  gold,  silver,  etc.  To 
clean  by  evaporation  of  condensed  gases  or  salts  on  gold  foil  or  crystal  gold,  for  the 
development  of  the  weldiug  property.  To  change  the  mutual  relation  of  an  alloy  for 
amalgam  and  the  mercury  with  which  it  is  to  be  combined.    Aging  the  alloy,  so  called. 

Antiseptic.  A  substance  or  remedy  which  opposes  the  development  of  septic 
conditions;  that  opposes,  delays,  hinders  or  prevents  those  decompositions  in  which 
poisonous,  septic,  or  disease-producing  compounds  are  formed;  such  as  the  putrefac- 
tions, fermentations,  etc. 

In  medicine,  an  agent  or  remedy  for  local  or  internal  use  which  opposes,  delays, 
hinders  or  prevents  the  development  of,  or  the  systemic  effects  from  the  absorption 
of,  toxic  compounds  formed  by  those  decompositions  occurring  in  suppurating  wounds, 
abscesses,  ulcers,  or  similar  conditions.  See  note  on  antiseptic,  disinfectant  and  germi- 
cide. 

Note  :     Antiseptic,  Disinfectant,  Germicide. 

The  words  antiseptic  and  disinfectant  were  in  general  use  before  the  relation  of  microGrganisms 
to  the  decompositions  and  to  disease,  as  now  understood,  was  discovered.  Though  the  old  form  of 
definition  is  generally  retained  in  dictionaries,  the  idea  of  the  meaning  of  the  terms  was  different 
from  that  of  the  present  time.  An  antiseptic  restrains  the  activity  of  microorganisms  and  gives  local 
parts  time  to  recover  and.  by  the  vital  powers  of  the  tissues,  to  furttier  restrain,  or  overcome  their 
growth  in  the  tissues  on  the  one  hand,  or  serves  to  ameliorate  the  effects  of  septic  poisons  already 
produced  and  absorbed  into  the  circulation  on  the  other.  After  this  idea  an  antiseptic  is  a  remedy 
of  local  or  of  systemic  usefulness.  To  be  useful  locally,  it  must  be  decisively  more  poisonous  to 
microorganisms  than  to  animal  tissues,  a  property  exhibited  in  greatest  degree  by  mild  solutions 
of  carbolic  acid,  "  1-2-3,"  and  mercuric  bichlorid.  For  general  systemic  use,  alcohol  and  cinchona 
are  examples. 

In  the  original  use  of  the  word  disinfectant,  the  agent  so  named  was  supposed  to  destroy  the 
noxious  products  of  decomposition,  to  render  them  non-poisonous,  or  to  destroy  or  remove  foul  odors 
or  emanations  from  decomposing  material.  With  increasing  knowledge  of  the  relation  of  micro- 
organisms to  the  decompositions  and  to  the  formation  of  foul  odors  and  of  disease-producing  poisons, 
or  toxins,  so  called,  the  idea  expressed  by  the  word  disinfectant  has  become  changed  to  that  of  the 
removal  or  destruction  of  the  actual  microHrganisms,  plasmocites,  etc.,  which  constitute  the  virus 
of  disease  and  are  responsible  for  the  decompositions  and  the  formation  of  the  noxious  compounds. 
This  may  be  done  by  any  means  at  hand,  as  by  washing  them  away  from  the  hands  or  from  instru- 
ments by  soap  and  water  with  the  brush,  destroying  them  by  heat  or  by  use  of  chemical  agents,  such 
as  gerrfticidcs. 

The  word  gei-micide  is  a  later  development  and  means  an  agent  that  actually  destroys  the  life 
of  microBrganisms.  plasmocites,  etc.,  which  constitute  the  actual  virus  of  infectious  diseases.  AU 
germicides  are  poisons.  It  is  only  when  in  attenuated  solutions  they  are  more  poisonous  to  micro- 
organisms than  to  the  animal  tissues  or  cells  that  they  may  be  used  as  antiseptics.  Inanimate  sub- 
stances, such  as  instruments,  clothing,  bedding,  rooms,  etc.,  may  properly  be  disinfected  with  genm- 
cides  when  the  chemical  relations  of  the  substances  to  each  other  are  such  that  material  injury  to  the 
articles  disinfected  will  not  occur.  When  sufficient  heat  can  be  used,  it  is  usually  the  best  and  safest 
disinfectant.  For  certain  purposes,  gaseous  germicides,  such  as  sulphurous  acid  obtained  by  burning 
sulphur,  or  formalin  may  be  employed.  These  are  readily  removed  by  the  free  admission  of  air  after 
they  have  done  their  work  in  the  disinfection  of  rooms,  clothing,  bedding,  etc. 

According  to  this  view,  an  antiseptic  is  a  medicinal  agent  which  may  be  of  use  in  topical  appli- 
cations or  as  an  internal  remedy.  Disinfectants  and  germicides  are  extra  medical,  and  are  chemical, 
mechanical,  or  physical  agents.  There  are,  however,  some  special  conditions  in  which  it  is  wise  to 
use  a  germicide  on  living  tissues.  As,  for  instance,  if  a  person  has  broken  the  skm  on  the  hand  or 
a  finger  while  handling  a  cadaver,  or  dangerous  surgical  material,  it  is  much  better  to  destroy  at 
once  the  possible  infectious  material,  together  with  a  limited  amount  of  tissue,  as  may  be  done  with 
95  per  cent  carbolic  acid  or  with  concentrated  formalin,  rather  than  nin  the  risk  of  grave  disease. 
Within  such  limits  only  can  disinfectants  or  germicides  be  used  as  medicines. 

Apex.  The  terminal  end  of  a  cone;  a  conical  end.  The  terminal  end  of  a  root  of 
a  tooth. 

Apical.    Pertaining  to  the  apex  or  conical  endings  of  the  roots  of  teeth. 

Apical  fokamen.  The  minute  opening  of  the  pulp  canal  at  the  apex  of  the  root 
of  a  tooth. 


282  PATHOLOGY    OF    THE    HABD   TISSUES   OF    THE    TEETH. 

Apical  space.  The  space  between  the  bone,  or  wall  of  the  alveolus,  and  the  apex 
of  the  root  of  a  tooth.  This  space  is  filled  with  the  soft  tissues  of  the  peridental  mem- 
brane, and  is  the  seat  of  alveolar  abscess. 

Approximate.  Next  to,  nearest  to.  To  draw  near  to.  Occasionally  employed  to 
designate  the  distal  or  mesial  surface  of  a  tooth.    See  Proximal. 

Arch.  An  arc  or  portion  of  a  circle.  Any  object  in  nature  or  art  which  is  curved, 
like  an  arc.    The  dental  arch,  the  arrangement  of  the  teeth  in  a  bow  shape  or  are. 

Aseptic.  The  condition  of  freedom  from  sepsis  or  freedom  from  microorganisms 
which  might  possibly  produce  a  condition  of  sepsis. 

Aseptic  opeeating.  To  make  the  conditions  such  as  to  prevent  the  entrance  of 
microorganisms  during  an  operation. 

Aseptic  wound.     A  wound  not  infected  with  microorganisms. 

Asphyxia.    Suspended  animation  from  sufEocation. 

Atrophy.  "Latin,  Atrophia,  without  nourishment.  A,  without;  trophia,  nour- 
ishment. ' ' — Webster. 

A  result  of  defect  of,  or  a  failure  of,  nutrition  of  a  part  which  limits  its  forma- 
tion. A  diminution  of  the  size  of  a  part,  or  a  wasting  due  to  defective  nutrition. 
Of  the  teeth:  a  failure  in  the  formation  of  certain  parts  of  the  enamel  and  dentin 
because  of  a  failure  of  nutrition  at  the  time  those  particular  parts  should  have  been 
formed.  This  results  in  a  dwarfing  of  certain  parts  of  the  tooth  and  causes  it  to  be 
malformed. 

A  wasting  of  certain  parts  or  organs  of  the  body  because  of  disease  affecting 
the  trophic  nerves.  Under  conditions  on  non-use  of  muscles  from  disease  or  accident 
they  waste  away  from  lack  of  nutrition.  The  term  atrophy  is  applied  to  many  condi- 
tions characterized  by  wasting  of  parts  due  to  disease  of  the  trophic  nerves  supplying 
the  part  and  consequent  failure  of  nutrition.     Syn.  Hypoplasia. 

Atrophy  marks.  The  peculiar  marks  left  on  the  teeth  by  reason  of  a  failure  of 
nutrition  during  their  development. 

Axial.    Pertaining  to  the  long  axis  of  a  tooth.    See  Axial  Surface. 

Axial  angles  or  teeth.  The  line  angles  that  are  parallel  with  the  long  axes  of 
the  teeth  are  called  axial  angles.  They  are  the  mesio-buccal  and  raesio-labial,  disto- 
buccal  and  disto-labial,  mesio-lingual  and  disto-lingual  angles. 

Axial  cavities.  Cavities  beginning  in  any  of  the  axial  surfaces  of  the  teeth;  as 
the  mesial,  buccal  or  labial,  distal  and  lingual  surfaces. 

Axial  surfaces.  Those  surfaces  of  the  teeth  that  are  parallel  with  their  long 
axes.    They  are  labial  or  buccal,  lingual,  mesial  and  distal  surfaces. 

Axial  wall  of  cavities.  A  cavity  wall  that  is  parallel  with  the  long  axis  of  a 
tooth  and  covers  the  pulp  chamber,  is  called  the  axial  wall. 

Axial  walls  of  pulp  chambers.  Those  walls  that  are  parallel  with  the  long  axes 
of  the  teeth ;    the  mesial,  distal,  buccal  and  lingual  walls. 

Axio-Bucco-LINGUAL  PLANE.  A  plane  passing  through  any  part  of  a  tooth  from 
buccal  to  lingual  parallel  with  its  long  axis.    See  Figure  11,  Vol.  2. 

Axio-LABio-LiNGUAL  PLANE.  A  plane  passing  through  any  part  of  an  incisor  or 
cuspid  tooth  from  labial  to  lingual  parallel  vrith  its  long  axis. 

Axio-MESio-DisTAL  PLANE.  A  plane  passiuf;  through  any  part  of  a  tooth  mesio- 
distally  parallel  with  its  long  axis.   See  also  Mesio-distal  Plane.   See  Figure  10,  Vol.  2. 

Bacillus.     (PI.  Bacilli.)     A  rod-shaped  bacterium. 

Bacteria.  A  class  of  microscopic  fungi  destitute  of  chlorophyl.  They  follow 
more  or  less  closely  four  forms:      (1)  the  sphere,  (2)  the  rod,  (3)  the  spirilla,  (4) 


GLOSSARY    OF    TECHNICAL   TERMS    AND    PHRASES.  283 

the  thread  forms.     They  are  closely  associated  with  the  fermentations,  putrefactions 
and  other  decompositions.     They  incite  a  number  of  special  diseases  in  man. 

Bell  crowned.  A  tooth  in  which  the  mesio-distal  diameter  of  the  crown  is 
much  greater  than  that  of  the  neck. 

Bevel.  To  cut  a  bevel  angle ;  to  slope  the  edge  or  surface  of.  To  deviate  or 
incline  from  an  angle  of  90  degrees,  as  a  surface;  to  slant.  (Webster.)  To  slope 
the  outer  edge  of  the  surface  of  the  enamel  wall  of  a  cavity.  See  Figure  103,  a, 
Vol.  2.  To  grind  tlie  flat  side  of  the  blade  of  an  instrument  at  an  inclination  to 
form  a  cutting  edge. 

BiBEVELED.  Having  a  bevel  on  two  sides  of  a  blade.  Bibeveled  to  a  point,  as 
in  drills,  for  cutting  while  being  rotated. 

Bibulous  paper.  A  specially  prepared  paper  used  as  an  absorbent  for  drying 
cavities  in  teeth. 

Bicuspid.  A  tooth  with  two  cusps.  There  are  eight  bicuspids;  two  on  each 
side  of  the  upper  jaw,  and  two  on  each  side  of  the  lower  jaw.  They  are  named 
right  and  left  upper  first  and  second,  and  right  and  left  lower  first  and  second 
bicuspids.  They  are  situated  between  the  cuspids  and  molars.  In  the  nomenclature 
of  comparative  dental  anatomy  the  bicuspids  are  called  premolars. 

Bite.    See  The  Bite. 

BoLEY  GAUGE.  So  named  after  the  person  who  designed  it.  Originally  a  watch 
maker's  gauge.  It  has  been  found  an  especially  convenient  instrument  for  the  den- 
tist to  use  for  all  kinds  of  delicate  measurements.    It  is  in  the  metric  system. 

Bone  corpuscles.     The  soft  cells  that  persist  in  bone  after  calcification. 

Border  op  the  alveolar  process.  The  thin  edge  of  the  alveolar  process  sur- 
rounding the  necks  of  the  teeth. 

Broach.  A  delicate  flexible  steel  instrument  for  cleaning  pulp  canals  in  teeth. 
There  are  several  varieties;    the  barbed  broach,  smooth  broach,  spiral  broach,  etc. 

Buccal.     Pertaining  to  the  cheek;    toward  the  cheek;     next  to  the  cheek,  etc. 

Buccal  cavities.  Cavities  formed  by  decay  beginning  in  the  buccal  surfaces  of 
the  teeth.  They  include  buccal  pit  cavities  and  smooth  surface,  or  gingival  third 
buccal  cavities. 

Buccal  sxtrface.     The  surface  of  a  tooth  next  to  the  cheek. 

BuccoGiNGiVAL  RIDGE.  A  prominent  ridge  near  the  gingival  line  on  the  buccal 
surface  of  the  deciduous  molars.  It  is  especially  prominent  on  the  deciduous  first 
molars. 

Bucco-LINGUAL.  From  the  cheek  toward  the  tongue;  as  the  bueco-Ungual  diam- 
eter of  the  crown  of  a  lower  first  molar. 

Bucco-LINGUALLY.    A  direction  from  the  buccal  toward  the  Ungual. 

Bucco-LINGUAL  PLANE.     A  Contraction  of  axio-buceo-lingual  plane. 

Calcific.    Containing  salts  of  calcium. 

Calcification.  The  act  of  depositing  calcific  matter  or  calcium  salts  during 
growth.  The  bones  and  teeth  become  calcified.  Also  pathological  calcifications 
occur  in  several  parts  of  the  body. 

Calcification  lines  op  Eitzeus.  The  accretion  lines  in  the  enamel  were  first 
described  by  Eitzeus.     See  Lines  of  Accretion. 

Calculus.  The  calcium  salts  of  the  oral  secretions  deposited  upon  the  exposed 
parts   of  the  teeth  and   parts  of  roots   denuded  of  their  membranes;     as,  salivary 


284  PATHOLOGY    OP    THE    HABD    TISSUES    OF    THE    TEETH. 

calculus  and  senimal  calculus.     A  common  medical  term  for  stone,  as  "gall  stone," 
renal  calculus,  etc. 

Canal.    See  Eoot  Canal. 

Cabies.  Latin,  caries.  Only  one  form  of  the  noun  is  used  in  English;  it  has 
no  plural.     The  word  was  imperfect  in  its  inflections  in  the  Latin. 

Rottenness,  moldiness,  decay,  as  of  wood  or  timber.  Anthon. 

{Med.)  Ulceration  of  bone;  a  process  in  which  bone  disintegrates  and  is  car- 
ried away  piecemeal,  as  distinguished  from  necrosis  in  which  it  dies  in  masses. 
Webster. 

In  dentistry:  Decay  of  the  teeth,  in  which  cavities  are  formed  in  them  by 
gradual  decomposition.  The  only  change  of  the  form  in  the  use  of  the  word  in 
English  is  the  adjective  carious,  as  a  carious  tooth.     See  Decay. 

Carious.  A  condition  of  tissue  like  enamel  or  dentin,  or,  of  a  tooth,  affected 
with  dental  caries.  In  medicine  it  refers  to  a  condition  of  suppurative  disintegration 
of  bone. 

Cataphoresis.  Introduction  of  medicine  into  the  tissues  through  the  unbroken 
skin,  or  the  tubuli  of  the  dentin  of  a  tooth,  by  means  of  an  electric  current. 

Cavities,  buccal.    See  Buccal  Cavities. 

Cavities,  lingual.     See  Lingual  Cavities. 

Cavities,  occlusal.     See  Occlusal  Cavities. 

Cavities,  pit.     See  Pit  Cavities. 

Cavities,  proximal.     See  Proximal  Cavities. 

Cavities,  rules  for  naming.    See  Eules  for  Naming  Cavities. 

Cavities,  rules  tor  naming  angles  op.  See  Rules  for  Naming  Angles  of 
Cavities. 

Cavities,  smooth-surface.    See  Smooth-surface  Cavities. 

Cavity.  An  opening  in  any  substance  which  has  but  one  outlet  or  is  entirely 
closed.     Any  opening  into  a  tooth  formed  by  caries  or  artificially  made. 

Cavity,  complex.  A  cavity  involving  two  or  more  surfaces  of  a  tooth,  as  a 
disto-occlusal  cavity. 

Cavity  nomenclature.  In  dentistry,  a  system  of  nomenclature  applied  to  cav- 
ities in  teeth.  Under  this  term  is  included  all  of  the  names  of  cavities,  names  of 
cavity  walls,  of  angles  of  cavities  and  the  terms  of  cavity  description,  together  with 
the  rules  of  their  use. 

Cavity  preparation.  Those  operations  necessary  in  forming  cavities  in  teeth 
for  the  reception  of  fillings. 

Cavity  walls,  rules  for  naming.    See  Eules  for  Naming  Cavity  Walls. 

Cavo-SURFace  angle.  The  angle  formed  by  the  junction  of  the  cavity  wall  and 
the  surface  of  the  tooth.  Used  particularly  in  indicating  the  form  to  be  given  this 
angle  by  beveling  or  otherwise,  in  any  particular  part  of  the  line  of  the  enamel  mar- 
gin.   See  Figure  8,  c  s,  Vol.  2. 

Cement,  n.  An  adhesive  tilling  material,  like  oxyphosphate,  oxychlorid  of 
zinc,  etc. 

Cement,  v.  To  fasten  by  an  adhesive  substance.  Ad  inlay  or  cast  filling  is 
cemented  in  place. 

Cementum.  a  special  calcified  tissue  which  covers  the  roots  of  the  teeth.  It 
has  lacuna;  and  canaliculi,  but  dillcrs  from  bone  in  having  no  Haversian  canals. 


GLOSSAEY    OF    TECHNICAL   TEEMS    AND    PHRASES.  285 

Centigrade  One  hundredth  part  of  a  circle.  An  angle  of  twenty-five  centi- 
grades  is  a  right  angle  and  equals  ninety  degrees  of  the  astronomical  circle,  or  eight 
decrees"  manner's  circle.      One  centigrade  equals  three   and   six  tenths    (3  6) 

Ceevical.  a  Pertaining  to  the  cervix  or  neck.  Used  formerly  in  a  sense 
somewhat  similar  to  that  m  which  gingival  is  now  used.     See  Gingival. 

Cervix,  n.  Neck  The  portion  of  the  crown  of  the  tooth  near  its  junction  with 
the  root  has  been  called  the  cervix,  or  neck. 

f»ot^^'''':-f ??"  ''''«/°°-  1°  dentistry  this  is  reckoned  from  the  first  appearance  of 
teeth  until  the  roots  of  all  of  the  permanent  teeth,  except  the  third  molars,  have 
been  completely  formed.  It  is  only  after  that  time  that  the  teeth  can  bo  treated 
m  a  1  respects  as  the  teeth  of  the  adult.  This  is  usually  about  the  fifteenth  or  six- 
teenth year. 

Childhood  period  op  the  permanent  teeth.    The  period  from  the  first  appear- 
mXs     SeVpTgTreTsVrVoL  r*"  '^""  ""'*'  ^"^  ^""^  completed,  except  the' third 
Chitin.    The  hard  shell-like  covering  of  insects. 
Chitinoid.     Chitin-Iike;    resembling  the  hard  covering  of  insects. 
Chitinous.    Consisting  of  or  resembling  the  hard  covering  of  insects. 
Clamp  forceps.    A  special  forceps  for  placing  the  rubber  dam  clamp. 

*  v,*1j^^^'-  ®"^ber  dam.  An  instrument  made  to  set  on  teeth  over  the  rubber  dam 
to  hold  It  m  place,  or  over  which  the  rubber  dam  may  be  thrown.  It  is  made  of 
spring  steel  and  m  applying  it,  it  is  opened  with  a  special  forceps,  placed  in  position 
and  allowed  to  close  on  the  tooth  with  the  force  of  its  spring. 

Classipication  op  cavities  into  artificial  groups.  In  a  classification  of  cav- 
ities, it  IS  the  intention  to  group  together  in  classes  cavities  of  decay  that  require 
a  similar  line  of  treatment,  in  order  that  these  may  be  more  closely  associated. 

Class  1.  Cavities  beginning  in  structural  defects  in  the  teeth;  pits  and  fissures 
These  are  located  m  the  occlusal  surfaces  of  the  bicuspids  and  molars,  in  the  occlusal 
two-thirds  of  the  buccal  surfaces  of  the  molars,  in  the  lingual  surfaces  of  the  upoer 
mcisors,  and  occasionally  in  the  lingual  surfaces  of  the  upper  molars. 

Class  2.     Cavities  in  the  proximal  surfaces  of  the  bicuspids  and  molars. 

Class  3.  Cavities  in  the  proximal  surfaces  of  the  incisors  and  cuspids  which 
do  not  involve  the  removal  and  restoration  of  the  incisal  angle. 

Class  4.  Cavities  in  the  proximal  surfaces  of  the  incisors  which  do  require 
tne  removal  and  restoration  of  the  incisal  angle. 

Class  5.  Cavities  in  the  gingival  third  —  not  pit  cavities  -  of  the  labial,  buccal 
or  Ungual  surfaces  of  the  teeth. 

_        f^lasses  2,  3,  4  and  5  are  all  smooth-surface  cavities.     They  aU  occur  in  positions 
m  which  the  surfaces  of  the  teeth  are  habitually  unclean. 

_       Class  name,_  of  an  instrument.     A  name  appUed  to  a  definite  class  of  cuttine 
instruments  describing  the  form  of  blade;    as  hatchet,  hoe,  spoon,  etc. 

Cleavage.  The  Une  of  easy  splitting  of  crystalline  or  stratified  substances.  To 
split  along  the  length  of  the  grain;  as  in  splitting  wood.  The  act  of  splitting  the 
enamel  m  a  certain  direction  following  the  length  of  the  enamel  rods  which  form 
its  cleavage  lines. 

Cleave.    To  split. 

Cleoid.  (From  cle,  old  Saxon  for  claw,  and  oid,  Hke.)  A  claw-like  instrument 
used  m  excavating  cavities. 

Clot.    n.    A  soft,  semi-solidified  mass,  as  of  blood  or  lymph. 


286  PATHOLOGY    OF    THE    HABD    TISSUES   OF    THE    TEETH. 

Coagulate,    v.    To  form  a  coagulum  or  clot. 

Coagulation.    The  process  of  formiiig  a  clot  or  coagulum. 

Coagulum.    n.    A  clot.    A  soft  semi-solidified  mass,  as  of  blood  or  lymph. 

Coccus.     (PI.  Cocci.)     A  spherical  or  nearly  spherical  bacterium. 

Cohesion.  The  act  or  state  of  sticking  together;  close  union.  That  form  of 
attraction  by  which  the  particles  of  a  body  are  united  throughout  the  mass,  particle 
to  particle.  This  must  be  distinguished  from  adhesion,  which  unites  bodies  by  their 
surfaces  only.  It  is  only  bodies  that  have  a  common  property,  as  simple  elements, 
compounds  or  alloys  formed  of  them,  that  cohere. 

Cohesive.  A  property  of  annealed  gold  (foU  or  crystal)  which  causes  separate 
particles  to  stick  to  one  another,  as  they  are  welded,  when  placed  in  contact  by  heavy 
hand  or  mallet  pressure. 

Cohesive  gold.  Gold  in  the  form  of  foil  or  crystals,  the  surfaces  of  which  are 
clean  and  free  from  condensed  gases  or  salts  so  that  they  may  be  brought  into  actual 
contact.  Gold  foil  or  crystals  in  which  the  welding  property  is  partially  or  fully 
developed. 

Complex  cavity.  A  cavity  involving  two  or  more  surfaces  of  a  tooth,  as  a  disto- 
oeclusal  cavity. 

Contact  point.  The  point  on  the  proximal  surface  of  a  tooth  which  touches  a 
neighboring  tooth. 

Contemporaneous  calcification  lines.  The  portions  of  the  several  teeth 
which  are  undergoing  calcification  at  the  same  time.  A  representation  of  the  por- 
tions of  the  several  teeth  undergoing  calcification  at  the  same  time  by  drawing 
lines  over  pictures  or  diagrams  of  the  teeth. 

Contour,     n.     The  line  bounding  a  figure  or  body,  as  the  contour  of  a  tooth. 

Contour,  v.  To  make  a  contour  or  outline  of.  To  restore  the  original  outline 
of  a  carious  tooth  by  filling. 

Contra-angle.  Angles  formed  in  the  shank  of  an  instrument,  first  backward 
from  the  direction  of  the  cutting  edge  and  then  forward  to  form  the  blade  in  order 
that  the  working  edge  may  be  placed  near  the  long  axis  of  the  handle.  There  are 
binangle  and  triple-angle  contra-angles. 

Contea-angle  hand-piece,  for  the  dental  engine.  A  hand-piece  with  a  contra- 
angle  to  enable  one  to  reach  positions  diflBcult  or  impossible  with  a  straight  hand- 
piece.   See  Figure  25,  Vol.  2. 

Convenience  form.  In  cavity  preparation:  Such  special  form  as  may  be 
given  to  special  points  of  the  internal  parts  of  cavities  as  will  render  the  placing 
of  the  filling  more  convenient. 

Convenience  point.  A  small  depression  or  undercut  to  make  the  starting  of 
a  filling  more  convenient.     See  Figures  170-173,  Vol.  2. 

Crown.  That  portion  of  a  tooth  which  is  covered  with  enamel,  and  which  pro- 
jects from  the  tissues  in  which  the  root  is  fixed. 

Culture  media.  (PI.)  Substances  used  to  grow  microorganisms  upon,  or  in. 
They  may  be  fluid  or  semi-solid. 

Curled  enamel.  Enamel  in  which  the  enamel  rods  are  much  crooked  and  curled 
or  intertwined  with  each  other.     See  Figure  147,  Vol.  1. 

Cusp.  A  pronounced  elevation,  or  point,  on  the  surface  of  a  tooth,  more  espe- 
cially on  the  occlusal  surface. 

Cuspid.     A  tooth  with   one  point,  or  cusp.     There  are  four  cuspids:     one  on 


GLOSSARY    OF    TECHNICAL   TERMS    AND    PHRASES.  287 

either  side  in  each  jaw,  situated  at  the  angles  of  the  mouth.     In  the  nomenclature  of 
comparative  dental  anatomy  these  are  called  canine  teeth. 

Cutting  edge.  The  edge  formed  by  the  junction  of  the  labial  and  lingual  sur- 
faces of  the  incisor  and  cuspid  teeth.  In  the  cusjiids,  the  edge  is  raised  to  a  point 
near  its  center.  The  edge  of  excavators,  such  as  hatchets,  hoes,  etc.;  or  of  other 
cutting  instruments. 

Decay.  Latin,  Cadere,  to  fall.  To  decline,  to  fall,  to  become  less;  to  pass  gradu- 
ally from  a  sound,  prosperous  or  perfect  state  to  one  of  imperfection,  adversity  or 
dissolution.  To  waste  away,  to  decline,  to  fall,  to  become  weak,  corrupt  or  disinte- 
grated; to  rot;  to  perish;  as,  a  tree  decays;  fortunes  decay;  hopes  decay.— 
Webster. 

Any  wasting,  disintegration,  softening  or  deterioration  by  decomposition.  Decay 
of  the  teeth  is  widely  used  as  synonymous  with  caries  of  the  teeth. 

Deciduous.  That  which  will  be  shed.  Deciduous  teeth  are  those  that  are  shed 
at  periodical  stages  of  growth  of  the  person  or  animal.  Applied  to  the  teeth  of  child- 
hood.    They  are  also  called  temporary  teeth. 

Defoembd.    Out  of  the  normal  or  correct  form. 

Deformity.  Misbuilding  of  any  organ  or  part  by  which  it  is  imperfectly  formed; 
out  of  correct  form. 

Dental.    Pertaining  to  the  teeth. 

Dental  caries.  A  local  disease  of  the  teeth,  in  which  the  enamel  is  dissolved  by 
the  action  of  lactic  acid  as  a  waste  product  of  microorganisms  and  the  dentin  is  dis- 
integrated by  the  vital  activity  of  acid  producing  organismB  penetrating  the  dentinal 
tubules.     See  Caries. 

Dental  engine.     A  machine  for  the  use  of  rotary  motion  in  dental  operations. 

Dental  instrument  gauge.  An  instrument  designed  especially  for  the  measure- 
ment of  dental  instruments.    See  Figure  17,  Vol.  2. 

Dental  nomenclatitre.  The  particular  system  of  nomenclature  used  in  den- 
tistry. In  many  respects  it  is  different  from  the  nomenclature  of  comparative  dental 
anatomy. 

Dbntigeeous.     Containing  or  producing  teeth,  as  a  dentigerous  cyst  or  tumor. 

Dentin.    The  tissue  of  which  the  main  body  of  a  tooth  is  formed. 

Dentinal  fibrils.  The  living  fibers  filling  the  dentinal  tubules.  See  Fibrils  of 
Tomes. 

Dentin  wall.  That  portion  of  the  wall  of  a  cavity  that  is  composed  of  dentin. 
See  Figure  8,  DW,  Vol.  2. 

Dentition,  the.  The  teeth  of  the  person  or  animal  as  a  whole.  The  dentition 
of  the  monkey  is  very  similar  to  that  of  the  man. 

Dentocemental  junction.    The  line  of  junction  of  dentin  and  cementum. 

Dento-enamel  junction.  The  line  of  junction  of  the  dentin  and  enamel.  See 
Figure  8,  de.  Vol.  2. 

Developmental  grooves.  Fine  depressed  lines  in  the  enamel  of  a  tooth  which 
mark  the  junction  of  its  lobes. 

Developmentai,  lines.    See  developmental  grooves. 

Diagnosis.  The  art  or  process  of  determining  the  nature,  location  and  causes  of 
a  disease. 

Dialyze.  To  cause  soluble  salts  to  pass  through  an  animal  membrane  to  separate 
them  from  gummy  substances  with  which  they  are  associated  in  a  solution. 


288  PATHOLOGY   OF    THE    HABD    TISSUES   OF    THE    TEETH. 

DiALiZEE.    Ad  apparatus  for  dializing. 

Dialysis.  The  passing  of  soluble  salts  through  animal  membranes  to  free  them 
from  colloid  or  gummy  material  with  which  they  are  mixed. 

Diathesis.  A  particular  habit  or  disposition  of  body.  A  certain  natural  con- 
stitution of  body,  cells  and  fluids,  by  which  a  person  is  predisposed  to  certain  particu- 
lar diseases;  as  the  Hemorrhagic  diathesis,  a  tendency  toward  profuse  bleeding  from 
slight  cause;    Gouty  diathesis,  a  predisposition  toward  gout,  etc. 

Diathetic.    Pertaining  to  diathesis. 

DiFFEREXTiAL  DIAGNOSIS.  The  distinguishing  between  two  similar  diseases  by 
comparison  of  their  symptoms. 

Disinfectant.  An  agent  —  mechanical,  physical,  chemical  or  medicinal  —  that 
removes  or  destroys  the  virus  of  infectious  or  communicable  diseases  or  of  pus  for- 
mation. As  a  brush,  soap  and  water;  a  boiling  temperature,  the  germicides,  etc. 
See  note  on  antiseptic,  disinfectant  and  germicide  under  Antiseptic. 

Disk  or  disc.  Any  flat  circular  plate.  Disks  used  by  dentists  are  thin,  circular 
pieces  of  paper,  cloth  or  other  substance  charged  with  abrasive  powder  for  cutting 
or  poUshing  teeth  and  fillings.     They  are  used  in  the  dental  engine. 

Distal.  Away  from  the  median  line  of  the  face  following  the  curve  of  the 
dental  arch.  The  surfaces  of  the  teeth  most  distant  from  the  median  line  are  called 
distal  surfaces. 

Distal  angle.  A  contraction  of  disto-incisal  angle.  Used,  also,  instead  of 
disto-bucco-oecdusal  angle  (q.  v.) 

Distal  cavities.     Cavities  beginning  in  the  distal  surfaces  of  the  teeth. 

Distally.  adv.  A  direction  away  from  the  median  line  of  the  face  following 
the  curve  of  the  dental  arch. 

Disto-buccal  angle,  (a)  The  angle  formed  by  the  junction  of  the  distal  and 
buccal  surfaces  of  the  bicuspids  and  molars,  (b)  An  angle  formed  by  the  junction 
of  the  distal  and  buccal  walls  of  a  cavity. 

DlSTO-BDCCO-occLTJSAL  ANGLE.  The  angle  of  a  bicuspid  or  molar  tooth  formed 
by  the  junction  of  its  distal,  buccal  and  occlusal  surfaces  at  a  point. 

Disto-incisal  angle.  The  angle  of  an  incisor  or  cuspid  tooth  formed  by  the 
junction  of  the  distal  surface  and  cutting  edge,  or  incisal  surface.  See  Incisal 
surface. 

Disto-labial  angle.  The  angle  formed  by  the  union  of  the  distal  and  labial 
surfaces  of  incisors  and  cuspids. 

DiSTO-LiNQUAL  ANGLE,  (a)  The  angle  formed  by  the  junction  of  distal  and 
lingual  surfaces  of  any  of  the  teeth,  (b)  The  angle  formed  by  the  junction  of  the 
distal  and  Ungual  walls  of  a  cavity. 

Disto-lingdo-ocolusal  ANGLE.  The  angle  of  a  bicuspid  or  molar  tooth  formed 
by  the  junction  of  its  distal,  lingual  and  occlusal  surfaces  at  a  point. 

DiSTO-ocCLUSAL  ANGLE.  The  angle  formed  by  the  junction  of  the  distal  and 
occlusal  surfaces  of  the  bicuspids  and  molars.  It  forms  the  distal  marginal  ridge 
of  the  occlusal  surfaces  of  these  teeth. 

Drill.  A  cutting  instrument  for  boring  holes.  Usually  bibeveled,  but  may  be 
square  ended. 

Dynamometer.  An  instrument  for  the  registration  of  force  in  its  application 
in  mechanics,  or  in  testing  the  strength  of  materials.     See  Figures  164,  165,  Vol.  1. 

Embrasure.  The  open  space  on  either  side  of  the  contact  point,  to  the  occlusal 
(or  incisal)  of  the  septal  tissue.  These  are  called  the  buccal  (or  labial),  and  the 
lingual  embrasures.  It  is  through  those  that  food,  crushed  between  the  teeth  and 
divided  by  the  contact  points,  glides  upon  the  sloping  surfaces  of  the  sept.al  gingivae 
to  either  side  of  the  arch. 

Enamel.    The  tissue  covering  the  dentin  of  the  crown  portion  of  the  tooth. 


GLOSSARV    OF    TECHNICAL   TERMS    AND    PHRASES.  289 

Enamel  cap.    The  covering  of  the  crown  of  the  tooth,  composed  of  enamel. 

Enamel,  cukled.    See  Curled  enamel. 

Enamel  margin.  The  junction  of  a  wall  of  a  cavity  with  the  surface  of  the 
tooth.  It  is  continuous,  forming  the  outline  of  the  cavity.  See  Cavo-surface  angle, 
and  Outline  form. 

Enamel  rods.  Tlic  form  elements  of  which  the  enamel  is  made  up.  They  are 
in  the  form  of  minute  rods  of  extremely  hard  calcific  material.  These  are  cemented 
together  in  a  solid  mass  by  an  intervening  cement  sub.stance  that  leaves  no  openings. 
The  general  course  of  the  enamel  rods  is  from  the  dento-cnamel  junction  to  the  sur- 
face of  the  tooth.  On  all  parts  the  ends  of  the  enamel  rods  are  presented  to  the 
surface  of  the  tooth. 

E.NAMEL  RODS,  INCLINATION  OF.  Used  in  describing  either  normal  or  abnormal 
inclination  of  the  enamel  rods  from  a  direction  perpendicular  to  the  surface  of  the 
tooth.     See  Inclination. 

Enamel,  straight.    See  Straight  enamel. 

Enamel  vtall.  That  portion  of  the  wall  of  a  cavity  which  is  composed  of  enamel. 
See  Figure  8,  ew.  Vol.  2. 

Enzyme.  Any  digestive  body,  or  digestive  fluid,  such  as  pepsin,  trypsin,  ptyalin, 
pancreatin,  etc. 

Epulis.    A  tumor  upon  the  gum. 

Erosion.  A  defect  in  a  surface  of  a  tooth  characterized  by  a  progressive  loss  of 
substance,  leaving  a  polished  or  smooth  surface  which  can  not  be  accounted  for  by 
abrasion. 

Esthetic.  Pertaining  to  the  science  of  esthetics,  which  treats  of  the  pleasing 
and  beautiful. 

Etiology.  The  science  of  the  causes  of  disease.  This  includes  predisposing  and 
exciting  causes,  remote  and'  near,  general  and  local,  hereditary  and  immediate,  or 
acquired. 

Excavating  bur.  A  moderately  coarse  cut  bur  designed  for  use  in  the  prepara- 
tion of  carious  cavities  in  teeth  for  filling. 

Excavator.  A  cutting  instrument  having  a  sharp  blade,  shank,  and  shaft  or 
handle,  for  use  in  the  preparation  of  cavities  in  teeth  for  the  reception  of  fillings. 

Extension  for  prevention.  Extension  for  the  prevention  of  the  recurrence  of 
decay  after  a  filling  has  been  made.  This  extension  is  always  to  be  made  in  the 
preparation  of  proximal  and  gingival  third  cavities.  In  each  case  the  extension  is 
toward  the  axial  line  angles  of  the  tooth  for  the  reason  that  the  regions  of  these 
angles  are  the  least  liable  to  the  beginnings  of  caries  of  any  portion  of  the  circum- 
ference of  the  tooth  near  the  free  margins  of  the  gingivsB. 

Facet.  On  the  teeth;  a  worn  spot  made  by  the  rubbing  of  the  proximal  sur- 
faces of  adjoining  teeth.  A  slight  loss  of  the  substance  of  the  enamel  in  the  begin- 
ning of  erosion,  etc.  A  facet  may  also  be  made  by  grinding  with  a  fine  stone.  Facets 
occur  on  the  occlusal  surfaces  of  the  teeth  from  wear. 

Ferment.  A  substance  which  causes  chemical  and  physical  changes  in  fer- 
mentable substances  with  which  it  comes  in  contact.  Certain  soluble  ferments,  as 
pepsin,  pancreatin,  ptyalin,  etc.,  induce  an  action  similar  or  identical  with  digestion; 
but  do  not  induce  further  changes.  The  living  ferments,  microorganisms,  carry  the 
process  to  its  ultimate  ends  by  converting  the  fermentable  substances  into  other 
chemical  compounds. 

Fermentation.  Chemical  and  physical  changes  induced  by  certain  micro- 
organisms. A  form  of  decomposition.  There  are  a  number  of  distinct  fermentations, 
as  vinous   fermentation,  lactic   fermentation,   acetic   fermentation,  etc. 

29 


290  PATHOLOGY    OF    THE    HABD   TISSUES   OF    THE    TEETH. 

Festoon.  An  enlargement  of  that  part  of  the  interproximal  gingivae  occupying 
the  embrasures  at  the  angles  of  the  teeth  buccally  and  lingually,  but  more  commonly 
only  the  buccal  portion. 

FiBBlLS,  DENTINAL.  The  fibrils  occupying  the  dentinal  canals.  See  Fibrils  of 
Tomes. 

Fibrils  of  Tomes.  The  prolongations  from  the  odontoblasts  which  occupy  the 
dentinal  canals.  They  reach  from  the  pulp  chamber  to  the  enamel  or  cementum.  See 
Dentinal  fibrils. 

Filling,  n.  The  material  placed  in  a  cavity  in  a  tooth;  the  resultant  of  the 
act  of  placing  a  filling.     Syns. :    A  plug;    a  stopping. 

Filling,  v.  The  act  of  placing  filling  materials  into  a  cavity  of  the  tooth  or 
roots  of  teeth.     Syns:    Plugging;    stopping. 

Finger  positions.  The  positions  of  the  fingers  in  performing  dental  operations. 
A  systematization  of  the  nomenclature  of  finger  positions.  See  Figures  46-61,  inclu- 
sive, Vol.  2. 

Fissure.  A  fault  in  the  surface  of  a  tooth  caused  by  the  imperfect  joining  of 
the  enamel  of  the  different  lobes.  Fissures  occur  along  the  lines  of  the  developmental 
grooves,  and  more  rarely  along  the  lines  of  supplemental  grooves. 

Fissure  bur.  A  bur  in  the  form  of  a  solid  cylinder  with  even,  straight  or 
parallel  surfaces.    See  Figure  137,  Vol.  2. 

Fissure  cavity.  A  cavity  beginning  along  the  line  of  a  fissure.  The  terms 
"pit  cavities"  and  "fissure  cavities"  are  often  used. 

Fistula.  [L]  A  reed,  or  pipe.  An  abnormal  opening  from  a  normal  cavity 
to  the  surface  for  the  discharge  of  a  normal  secretion. 

' '  In  pathology,  a  narrow  passage  or  duct,  formed  by  disease  or  injury,  leading 
from  an  abscess  to  a  free  surface,  or  furnishing  an  abnormal  means  of  egress  from 
some  normal  cavity,  as  in  vesico-vaginal  fistula."     Century  Dictionary. 

"(Medical.)  A  long,  sinuous  pipe-like  ulcer,  with  a  narrow  orifice  and  without 
disposition  to  heal.  Hoblyn.  Fistulse  have  different  names  according  to  the  discharge 
which  they  afford,  and  the  organs  in  which  they  are  seated,  as  lachrymal,  biliary, 
salivary,  synovial,  urinary.     Dunglison. ' '     Worcester. 

"  (Medical.)  A  permanent  abnormal  opening  into  the  soft  parts  with  a  constant 
discharge;  a  deep,  narrow,  chronic  abscess;  an  abnormal  opening  between  an  internal 
cavity  and  another  cavity  or  on  the  surface,  as,  a  salivary  fistula ;  an  anal  fistula,  a 
recto-vaginal  fistula. ' '     Webster. 

"(Pathology.)  Any  abnormal  opening  into  a  natural  canal  or  hollow  organ. 
A  long,  narrow  canal  caused  by  diseased  action  and  not  disposed  to  heal  because  of 
morbid  conditions."     Standard  Dictionary. 

"An  unnatural  channel  leading  from  a  cutaneous  or  mucous  surface  to  another 
free  surface  or  terminating  blindly  in  the  substance  of  an  organ  or  part. ' '  Foster 's 
Medical  Dictionary. 

' '  An  abnormal  tube-like  passage  in  the  body. ' '     Gould. 

"A  narrow  track  or  canal  leading  from  a  free  surface,  and  extending  more  or 
less  deeply  to  some  seat  of  local  irritation;  or  it  may  be  constituting  an  abnormal 
communication  between  two  or  more  cavities,  as  in  the  case  of  a  vesico-vaginal  fis- 
tula. ' '    Quain. 

Note:  It  will  be  noticed  from  the  above  tluit  the  word  fistula  is  used  with  two  distinct  mean- 
ings :  one,  an  abnormal  passage  for  the  discharge  of  a  normal  secretion  from  a  normal  cavity,  as  a 
salivary  or  urinarv  fistula ;  the  other,  an  abnormal  passage  for  the  discharge  of  an  abnormal  secre- 
tion (pus)  from  an  abnormal  (abscess)  cavity.  The  first  of  these  meanings  seems  to  be  the  favored 
one,  and  in  view  of  the  fact  that  the  definition  of  the  word  sinus  as  applied  to  such  a  tract,  is  identi- 
cal with  the  second  meaning  of  fistula,  it  wo\ild  seem  to  be  very  desirable  to  use  the  woril  sinus  in 
•peaking  of  such  a  tract  from  which  pus  is  discharged,  and  the  word  fistula  in  speaking  of  such  a 
tract  from  which  a  normal  secretion  is  discharged. 

Formula  names.  A  system  of  naming  dental  instruments  based  on  the  measure- 
ment of  their  working  parts.     See  text. 

Fossa.     (PI.  Fossae.)     A  round,  or  angular  depression  in  the  surface  of  a  tooth. 


GLOSSAKY    OF    TECHNICAL   TERMS    AND    PHRASES.  291 

Fossffi  occur  mostly  in  the  occlusal  surfaces  of  the  molarH,  nud  in  the  lingiiul  surfaces 
of  the  incisors. 

Fungous.     Pertaining  to  the  fungi. 

Fungus.  (PI.  Fungi.)  The  lowest  order  of  plants.  They  are  destitute  of 
chlorophyl  and  grow  in  the  dark  as  well  as  in  the  light.  Microorganisms  belong  to 
this  class. 

Gelatinoid.  Gelatin-like.  Having  the  appearance  of  gelatin.  Used  in  describ- 
ing masses  that  have  the  general  appearance  of  gelatin  but  which  are  not  of  the  com- 
position  of  true   gelatin. 

Gelatinoid  plaques.  Masses  of  microorganisms  in  zooglea  form,  or  inclosed 
in  a  gelatinoid  substance  and  attached  to  the  teeth.     See  Zobglea. 

Germicide.  Any  agent  that  destroys  germs,  as  microorganisms,  plasmocites, 
etc.,  or  the  virus  of  infectious  diseases;  as  the  boiling  temperature,  mercuric. 
bichlorid,  formalin,  carbolic  acid,  etc.  See  note  on  antiseptic,  disinfectant  and 
germicide  under  Antiseptic. 

Gingiva.  (Plural,  Gingivae.)  That  portion  of  the  gum  tissue  covering  the 
alveolar  process,  surrounding  the  borders  of  the  enamel  of  the  teeth  next  to  the 
cemeutum  and  filling  the  interproximal  spaces.  Gums,  is  often  used  as  the  synonym 
of  gingivae  But  gums  includes  the  firm  fibrous  tissue  covering  the  palatal  processes, 
while  gingiva?  is  restricted  to  the  gum  tissue  close  about  the  teeth. 

Note  :  This  word  is  very  generally  used  in  the  plural  form.  It  is  derived  from  the  Latin : 
Gigno,  genui,  genitinu,  which  was  probably  obtained  from  the  Greek.  In  varying  forms  it  seems  to 
have  maintained  a  place  in  the  Latin  throughout  its  active  use  as  a  spoken  language.  A  large  number 
of  English  words  are  derived  from  the  various  Latin  forms.  Latin  dictionaries  define  the  original 
words  thus:  To  beget;  to  bear;  to  bring  forth;  to  produce.  In  the  passive  form;  to  be  born; 
to  spring ;  arise ;  proceed,  etc.  "  Quacumque  animal  parrient  in  capita  gignunt.  Pliny,  10,  64, 
Bring  forth  their  young  head  foremost.*'     Harper's  Latin-English  Dictionary. 

The  word  gingiva,  or  the  plural  gingiva,  seems  to  have  had  a  wide  use,  and  had  special  refer- 
ence to  that  portion  of  the  gums  which  gave  birth  to.  or  produced,  teeth ;  or  lay  immediately 
about  them,  as  in  this  idiomatic  expression,  "  Interdentum  et  gingivam.  Celcus,  6,  13";  literally, 
between  the  gums  and  the  teeth ;  but  meaning  in  a  close  place.  This  is  akin  to  "  by  the  skin  of  his 
teeth,"  sometimes  heard  in  English. 

The  Standard  Dictionary  —  Twentieth  Century  Edition  —  gives  the  plural  form  only  and  author- 
izes the  spelling  gingiva  instead  of  gingivae:  The  grmis ;  gingival,  of  or  pertaining  to  the  gums. 
Produced  by  aid  of  the  gums ;     as  gingival  sounds. 

The  American  Illustrated  Medical  Dictionary,  1902,  gives  Ging^iva,  Pi.  Gingiva :  The  gums ; 
the  fleshy  structure  that  covers  the  alveolar  border  of  the  jaw.  Gingival,  pertaining  to  the  gura  or 
gums. 

Gould's  Medical  Dictionary:  '*  Gingival.  Pertaining  to  the  giims.  Gingival  line.  A  blue  or 
purplish  line  along  the  gums  where  they  meet  the  teeth,  indicative  of  chronic  lead  poisoning.  Also 
a  reddish  line  along  the  gums,  sometimes  seen  in  tuberculosis.  Gingival  margin.  The  line,  or  edge 
of  the  gums  where  they  meet  the  teeth  ;     the  free  edge  of  the  gums." 

Dorland'a  Medical  Dictionary  gives  the  definition  of  gingivte:  "That  portion  of  the  gum  close 
about  the  teeth." 

In  looking  up  examples  of  the  use  of  the  word  in  the  Latin,  it  is  found  that  the  plural  form 
was  used  much  more  frequently  than  the  singular,  and  this  is  true  in  English.  It  is  the  same  in  the 
use  of  gum  and  gums. 

In  the  French  language,  the  word  is  gencieve,  gum  or  gums. 

Probably  if  we  had  an  English  adjective  derived  from  the  word  gum,  as  gumal,  we  would  not 
have  needed  the  Latin  term,  but  as  practically  all  of  the  adjectives  ending  in  al,  used  in  dental 
nomenclature,  are  of  Latin  origin,  such  an  adjective  form  of  the  old  Saxon  word,  gum,  would  look 
a  bit  out  of  place.     An  adjective  is  a  necessity. 

The  word  neck,  and  the  Latin  equivalent  cervix,  have  had  some  use  in  dentistry'  in  which  cervical 
has  been  the  adjective  form.  This  word  was  used  to  represent  a  constriction  or  a  supposed  constric- 
tion between  the  crown  of  the  tooth  and  its  root.  As  used,  its  meaning  was  much  too  vague  to  serve 
the  purposes  of  modern  dentistry.  Cervical  is  now  practically  obsolete,  but  the  word  neck  is  occa- 
sionally used  in  a  few  phrases. 

These  notes  have  been  written  after  the  book  proper  was  printed,  and  I  find  that  the  use  of  the 
word  is  always  with  reference  to  that  portion  of  the  gum  tissue  close  about  the  teeth.  The  word 
gum  is  used  as  synonymous  in  many  places.  In  a  good  many  expressions  it  is  preferred.  Wherever 
an  adjective  form  is  necessary,  however,  gingival  is  the  only  word  used. 

Gingival  line  is  always  used  to  represent  the  normal  line  of  the  attachment  of  the  gum  tissue 
to  the  tooth,  and  the  adjective  gingival  always  refers  to  that  line.  This  is  at  the  junction  of  the 
enamel  and  cementum.  The  adverb,  gingivaliy,  is  always  used  when  the  reference  is  to  the  crown 
of  a  tooth,  a  direction  toward  the  gingival  line.  If  it  is  used  with  reference  to  the  root  of  a  tooth, 
it  is  also  toward  the  gingival  line. 

I  have  generally,  but  not  always,  used  "  free  margin  of  the  gum,"  instead  of  free  margin  of  the 
gingiva,  to  represent  that  portion  lapping  onto  the  enamel  of  the  teeth.  Gum  line,  as  used,  means 
the  line  of  the  extreme  edge  of  the  free  margin  of  the  gingiva  that  laps  upon  the  enamel  of  the  teeth. 

The  fact  that  a  few  authors  and  a  few  dictionaries  have  used  "  gingival  line,"  to  represent  the 
line  of  dark  color  on  the  gingiva;  frequently  present  in  lead  poisoning,  can  cause  no  confusion  in  the 
use  of  these  words  in  dentistry.     This  can  not  be  said  to  be  in  general  use  in  medical  literature. 


292  PATHOLOGY    OF    THE    HARD    TISSUES   0¥    THE    TEETH. 

Gingival.  Pertainiug  to  the  gingival  line;  as  the  curvature  of  the  gingival  line; 
gingival  margin;  gingival  wall,  etc.  Pertaining  to  that  portion  of  the  gums  covering 
the  alveolar  processes  surrounding  the  borders  of  the  enamel  next  to  the  cementum 
and  filling  the  interproximal  spaces. 

Gingival  curvature.  The  deviation  of  the  gingival  line  from  the  horizontal 
in  its  course  around  the  neck  of  a  tooth ;    especially  of  the  incisors  and  cuspids. 

Gingival  line.  The  line  around  the  neck  of  a  tooth  at  which  the  gingiva  is 
attached.     The  line  of  junction  of  the  enamel  and  cementum. 

Gingivally.  a  direction  from  any  part  of  the  crown  toward  the  gingival  line  of 
a  tooth. 

Gingival  margin.  The  portion  of  the  crown,  or  a  surface  of  the  crown  of  a 
tooth  next  to  the  gingival  line.  The  margin  of  a  cavity  that  is  toward  or  next  to  the 
gingival  line.  * 

Gingival  margin  trimmers.  Instruments  for  beveling  the  eavo-surface  angles 
of  the  gingival  walls  of  proximal  cavities  in  the  bicuspids  and  molars. 

Gingivitis.  Inflammation  of  the  gingivje.  See  Ulitis.  While  the  term  gingivitis 
should  be  limited  to  inflammation  of  the  soft  tissues  immediately  about  the  teeth  and 
covering  the  borders  of  the  alveolar  processes,  the  term  ulitis  includes  the  wider 
inflammation  areas  that  include  the  roof  of  the  mouth  and  other  parts. 

Glutinoid.  Glutin-like.  Any  semisolid  which  resembles  glutin,  or  is  glutinous; 
sticky,  adhesive. 

Gnathodynamometer.  An  instrument  for  measuring  in  pounds,  kilograms,  etc., 
the  force  exerted  in  closing  the  teeth.     See  Figures  162,  163,  Vol.  1. 

Gold  foil.  Thin  sheets  of  gold  prepared  for  filling  teeth.  The  thickness  is 
expressed  in  numbers,  1,  2,  3,  4,  etc.,  up  to  120.  The  numbers  express  the  number  of 
grains  of  gold  in  a  sheet  four  inches  square.  Light  foils  are  those  below  No.  10. 
The  heavy  foils  are  those  above  No.  10. 

Gold,  non-cohesive.  Gold  in  the  form  of  foil  or  crystals  in  which  the  welding 
property  is  obscured,  usually  by  the  condensation  of  some  gaseous  substance  upon  it, 
or  a  film  of  a  salt  from  the  union  of  two  or  more  gases. 

Grasps,  instrument.    See  Instrument  grasps. 

Grasps,  rubber  dam.     See  Rubber  dam  grasps. 

Groove.    A  long-shaped  depression  in  the  surface  of  a  tooth. 

Gums.  The  harder  fleshy  covering  of  the  bones  of  the  mouth,  particularly  of 
the  roof  of  the  mouth  and  the  alveolar  processes.     See  Gingiva. 

Gum  septums.  That  portion  of  the  giuns  or  gingiva  that  occupies  the  inter- 
proximal spaces. 

H.\.tch  clamp.  So  called  after  the  person  who  designed  it.  A  rubber  dam  clamp 
of  special  pattern  for  use  in  treating  gingival  third  cavities.  It  may  be  used  on  all 
teeth  except  the  molars. 

Haversian  bone.     Bone  composed  of  Haversian  .systems. 

Haversian  canal.  Eistolof/y.  A  canal  which  occupies  the  center  of  a  Haversian 
system. 

Haversian  system.  Histolor/it.  A  long,  cylindrical  area  in  bone,  usually  placed 
lengthwise  of  the  long  bones,  composed  of  a  central  canal  surrounded  by  a  number 
of  concentric  rings  or  layers  of  bone  corpuscles. 

Hemorrhage.  Escape  of  blood  from  the  blood  vessels.  Capillary  H.,  from  the 
capillaries.    Venous  H.,  from  the  veins.     Arterial  H.,  from  the  arteries. 

Hemostatic.     A  medicinal  agent  that  checks  or  arrests  the  flow  of  blood. 


OLOSSARV    OF    TECHNICAL    TEKJVIS    AND    PHRASES.  293 

IIoRizoNTAL  PLANE.  A  plane  through  any  part  of  a  tooth  at  right  angles  to  its 
length.     See  Figure  9,  Vol.  2. 

IToBN.  A  slender,  or  blunt  pointed  process  of  the  pulp  of  a  tooth  extending 
toward  the  point  of  a  cusp  is  called  a  horn  of  the  pulp,  or  a  pulpal  horn. 

HoEN  Of  THE  PULP.  A  prooess  of  pulj)  tissue  extending  toward  the  cusp  of  a 
tooth. 

Horn  of  the  pulp  chamber.  The  projection  of  the  pulp  chanibor  of  a  tooth 
toward  a  cusp.     It  is,  in  normal  conditions,  occupied  by  the  horn  of  the  pulp. 

Hyperemia.  An  e.xcess  of  blood  in  the  blood  vessels  of  a  part.  Active  hyperemia, 
an  excessive  inflow  of  blood  to  a  part.  Passive  hyperemia,  diminished  outflow  of 
blood  from  a  part ;  or  a  filling  of  the  tissues  of  a  part  with  blood  because  of  some 
interference  with  the  circulation  of  the  blood  through  the  part.  These  are  also  called 
arterial  hyperemia  and  venous  hyperemia. 

Hyperesthesia.    Abnormally  increased  sensitiveness  to  painful  impressions. 

Hypersensitive.  Excessive  sensibility  to  irritation,  thermal,  chemical  or  mechan- 
ical.    Hypersensitive  pulp.     Hypersensitive  dentin.     See  Hyposensitive. 

Hypersensitiveness.  a  condition  of  abnormally  increased  sensitiveness  to 
pain,  or  abnormally  increased  pain  from  definite  causes  which  usually  excite  pain. 
See  Hypoesthesia. 

Hypoesthesia.  Diminished  sensitiveness  to  impressions  which  usually  excite 
pain. 

Hypoplasia.  Abnormally  diminished  growth  of  a  part.  A  partial  failure  of 
development  because  of  lack  of  the  ordinary  fuU  and  complete  growth.   Syn.  Atrophy. 

Hyposensitiveness.  Abnormally  diminished  pain  from  definite  causes  which 
excite  pain. 

Hutchinson  tooth.  An  incisor  tooth  presenting  a  notch  or  defect  in  the  cen- 
tral portion  of  the  incisal  edge,  caused  by  atrophy. 

Immediate  root  filling.  Boot  filling  inserted  immediately  after  removal  of  the 
pulp  of  the  tooth. 

Immobile.  The  opposite  of  mobile.  The  features  of  the  person  present  less 
than  the  usual  flexibility  of  muscular  motion  in  speaking,  laughing,  etc.     See  Mobile. 

Impacted  teeth.  Teeth  confined  in  the  jaw  and  prevented  from  erupting. 
Teeth  that  have  taken  a  wrong  direction  and  have  failed  to  erupt. 

Implantation.  The  operation  of  forming  an  artificial  alveolus  in  the  alveolar 
process  and  inserting  in  it  a  natural  tooth. 

Incisal.  Pertaining  to  the  cutting  edges  of  the  incisors  and  cuspids,  which  in 
the  use  of  the  word  incisal  are  regarded  as  incisal  surfaces. 

Incisal  margin.  That  margin  of  a  surface  of  an  incisor  or  a  cuspid  tooth 
formed  by  the  incisal  surface  or  cutting  edge;  as  the  incisal  margin  of  the  labial 
surface  of  the  central  incisor;  the  cavo-surface  angle  of  the  incisal  wall  of  a  labial 
or  lingual  cavity,  etc. 

Incisal  surface.  The  cutting  edge  of  the  incisors  and  cuspids  are  sometimes 
called  incisal  surfaces. 

Incisor.  A  tooth  with  a  cutting  edge.  There  are  four  incisors  in  the  upper 
jaw,  and  four  in  the  lower  jaw.  They  are  called  the  upper  and  lower  right  and  left 
central,  and  the  upper  and  lower  right  and  left  lateral  incisors. 

Inclination.  Of  a  tooth:  The  deviation  of  the  long  axis  of  a  tooth  from  the 
perpendicular  line;    as  the  mesial  inclination  of  the  incisors.     Of  a  surface:      The 


294  PATHOLOGY    OF    THE    HAED    TISSUES    OF    THE    TEETH. 

deviation  of  a  portion  of  the  surface  of  a  tooth  from  the  general  plane  of  that  sur- 
face. Inclinations  of  the  teeth  become  abnormal  when  they  are  such  as  to  disturb 
the  harmony  of  the  positions  of  the  teeth  in  the  arch.  Used  also  in  describing  the 
angles  with  the  surface  of  the  tooth  at  which  the  walls  of  a  cavity  may  be  cut,  or  of 
the  relation  of  opposing  walls  to  each  other,  as  outward  inclination,  inward  inclination, 
etc.  Also,  inclination  of  enamel  rods  from  a  line  perpendicular  to  the  surface  of  a 
tooth. 

Inclination  of  enamel  rods.  Used  in  describing  either  normal  or  abnormal 
inclinations  of  the  enamel  rods  from  a  direction  perpendicular  to  the  surface  of 
the  tooth. 

Incline.     See  Inclination. 

Inlay.  A  porcelain  or  metal  filling  for  inserting  in  a  cavity  prepared  for  it 
in  a  tooth;    and  retained  by  cement. 

Instrumentation.  All  uses  of  instruments  in  dentistry  are  included  under  this 
term. 

Instrument  grasps.  Definite  ways  of  grasping  instruments  suited  to  their 
uses,  such  as  the  pen  grasp,  thrust  grasp,  etc. 

Interglobular  spaces.  Spaces  left  without  calcium  salts  during  the  develop- 
ment, or  growth,  of  the  dentin.  Many  of  these  appear  as  spaces  between  imperfectly 
fused  globules. 

Interproximal.  Between  adjoining  surfaces.  The  space  between  adjoining 
teeth  as  they  stand  in  the  line  of  the  arch. 

Inteepeosimal  Space.  The  space  bounded  by  the  proximal  surfaces  of  adjoining 
teeth,  by  the  planes  of  their  buccal  (or  labial),  occlusal  (or  incisal),  and  lingual 
surfaces,  and  by  the  crest  of  the  septum  of  the  alveolar  process  between  them.  The 
interproximal  space  is  divided  into  ( 1 )  the  septal  space,  which  is  normally  filled  with 
the  interproximal  gum  septum,  or  septal  gingivae;  (2)  the  buccal  (or  labial) 
embrasure,  the  open  space  to  the  buccal  (or  labial)  of  the  contact  point  and  to  the 
occlusal  (or  incisal)  of  the  septal  tissue;  (3)  the  lingual  embrasure,  the  open  space 
to  the  lingual  of  the  contact  point  and  to  the  occlusal  (or  incisal)  of  the  septal 
tissue. 

Inverted  cone  bur.  A  bur  head  in  the  form  of  a  cone,  the  apex  of  which  forms 
the  attachment  with  its  shaft.     See  Figures  170,  171,  Vol.  2. 

Inverted  pen  grasp.  In  this  the  fingers  are  so  bent  as  to  invert  the  ordinary 
position  of  the  instrument.     Used  in  some  special  positions.     See  Figure  55,  Vol.  2. 

Invtard  inclination.  In  comparative  dental  anatomy,  a  tooth  that  is  inclined 
lingually.     In  dentistry,  lingual  inclination  should  be  used. 

Labial.    Pertaining  to  the  lips.     Toward  the  lips. 

Labial  cavities.  Cavities  beginning  in  the  labial  surfaces  of  the  incisors  and 
cuspids. 

Labial  inclination.    An  inclination  or  leaning  of  a  tooth  labially. 

Labially.    a  direction  toward  the  Ups. 

Labial  surface.  The  surface  of  a  tooth  next  to  the  lips.  The  incisors  and 
cuspids  have  labial  surfaces. 

Labio-lingual.  From  the  lips  toward  the  tongue;  as  the  labio-lingual  diameter 
of  the  central  incisor. 

Labio-lingually.    a  direction  from  the  lips  toward  the  tongue. 

Lancet.     An  instrument  with  small  blade  for  incising  soft  tissues. 

Lateral  alveolar  abscess.  An  abscess  located  in  the  peridental  membrane 
anywhere  along  the  sides  of  the  root  of  a  tooth  and  not  involving  the  apical  space. 
The  pulp  of  the  tooth  may  be  alive.  Lateral  alveolar  abscesses  occur  most  frequently 
in  phagedenic  pericementitis  but  may  occur  from  accidental  causes,  such  as  thrusting 
a  spicula  of  wood  from  a  toothpick  into  the  peridental  membrane,  etc. 


GLOSSARY    OF    TECHNICAL   TERMS    AND    PHRASES.  295 

Ligature.  Anything  that  binds.  A  cord  or  thread  for  tying  blood  vessels,  or 
for  tying  around  the  teeth. 

LiGATUBES.  Threads  of  floss  or  twisted  silk  used  as  aids  in  adjusting  the  rubber 
dam,  tying  it  in  place,  tying  on  matrices,  etc. 

Line  angles.  Of  the  teeth :  Those  angles  formed  by  the  junction  of  two  sur- 
faces along  a  line;  as  the  mesio-buccal  angle,  disto-buccal  angle,  etc.  Of  cavities: 
Those  angles  formed  by  the  junction  of  two  cavity  walls  along  a  line;  as  disto- 
buccal  angle  or  axio-gingival  angle.     See  Sots  of  Line  Angles. 

Lines  op  accretion.  The  lines  of  accretion  or  of  contemporaneous  growth 
seen  in  the  enamel  of  the  teeth.  They  are  also  known  as  the  lines  of  Ketzius,  the 
person  who  first  described  them.    See  Accretion. 

Lingual.    Next  to,  or  toward  the  tongue;    as  lingual  surface. 

Lingual  cavities.    Cavities  beginning  in  the  lingual  surfaces  of  the  teeth. 

Lingual  inclination.  Said  of  teeth  when  they  are  inclined  toward  the  tongue, 
or  of  a  cavity  wall  that  inclines  toward  the  tongue;  anything  inclined  toward  the 
tongue. 

Lingually.     a  direction  toward  the  tongue. 

Lingual  surface.  A  surface  of  a  tooth  next  to  the  tongue.  All  of  the  teeth 
have  lingual  surfaces.    In  comparative  dental  anatomy  these  are  called  inner  surfaces. 

Linguodistal  inclination.  An  inclination  of  the  teeth  to  the  lingual  and 
distal  often  seen  in  the  lower  bicuspids  when  a  lower  first  molar  has  been  lost  in 
childhood  or  youth.    Anything  inclined  linguo-distally. 

LiNGUO-GiNQlVAL  FISSURE.  A  fissure  occurring  occasionally  in  the  lingual  sur- 
face of  the  upper  incisors.  It  usually  separates  the  lingual  lobe  from  one  of  the 
marginal  ridges  and  extends  into  the  cementum. 

LlNGUOGlNGlVAL  RIDGE.  A  ridge  near  the  gum  on  the  lingual  surface  of  the 
incisors  and  cuspids.     It  is  on  the  lingual  lobe. 

Lobe.  A  division  of  a  tooth  formed  from  any  one  of  the  separate  points  of 
the  beginning  of  calcification. 

Malocclusion.  An  occlusion  of  the  teeth  that  is  not  in  accordance  with  the 
usual  anatomical  rule,  or  form. 

Malposed.     Out  of  the  correct  or  normal  position. 

Malposition.     Any  wrong  position;    abnormal  position. 

Mammelons.  The  three  rounded  prominences  seen  on  the  cutting  edges  of  the 
incisors  when  they  first  come  through  the  gums. — Magitot. 

Mandrel.  A  shaft  or  spindle  in  which  a  disk  or  stone  is  held  for  rotation. 
Used  in  the  dental  engine. 

Manudynamometek.  An  instrument  by  which  the  force  exerted  by  an  instru- 
ment thrust  may  be  measured.     See  Fig.  31,  Vol.  II. 

Marginal  lines,  of  a  cavity.    The  lines  of  the  cavity  outline. 

Marginal  ridge.  The  ridges,  or  elevations  of  enamel  on  the  margins  of  the 
occlusal  surfaces  of  the  bicuspids  and  molars,  and  on  the  mesial  and  distal  margins 
of  the  lingual  surface  of  the  incisors  and  cuspids. 

Massage.  Systematic  friction  for  the  purpose  of  preventing  or  curing  disease. 
Friction  of  the  gums  with  the  finger,  or  specially  designed  brush,  as  a  prophylactic 
measure. 

Masticate,  v.  To  chew  food.  To  reduce  food  to  a  pulp  by  trituration  and 
mixing  with  solvents,  as  in  chewing  and  in  the  insalivation  of  food  in  the  mouth. 

Mastication,  n.  The  act  of  chewing;  the  triturating  of  the  solid  foodstuffs 
between  the  teeth,  by  which  they  are  reduced  to  a  pulpy  mass.  One  of  the  functions 
of  the  teeth. 


296  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

Matrix.  A  mold  in  which  anything  is  formed.  A  thin  sheet  of  metal  closely 
fastened  on  a  tooth  to  form  a  fourth  surrounding  wall  of  a  proximal  cavity  in  a 
tooth.  A  platimim  or  gold  lining  of  a  cavity  in  which  a  porcelain  or  gold  inlay  is 
baked  or  fused.  The  mold  formed  of  an  investment  into  which  gold  or  other  metals 
are  cast. 

Median  line.    The  anterior-posterior  perpendicular  central  line  of  the  body. 

Mesial.  Toward  the  median  line.  Those  surfaces  of  the  teeth  which,  as  they 
stand  in  the  arch,  and  following  its  curve,  are  toward  the  median  line,  are  called 
mesial  surfaces. 

Mesial  angle.  A  contraction  of  mesio-incisal  angle,  also  of  mesio-bucco-occlusal 
angle  (q.  v.) 

Mesial  cavities.    Cavities  in  the  mesial  surfaces  of  the  teeth. 

Mesial  inclination.    An  inclination  or  leaning  of  a  tooth  mesially. 

Mesially.  A  direction  toward  the  median  line  following  the  curve  of  the  arch 
formed  by  the  teeth. 

Mesio-buccal  angle.  The  angle  formed  by  the  union  of  the  mesial  and  buccal 
surfaces  of  the  bicuspids  and  molars. 

Mesio-bucco-occlusal  angle.  The  angle  formed  by  the  junction  of  the  mesial, 
buccal  and  occlusal  surfaces  of  the  bicuspids  and  molars  at  a  point. 

Mesio-distal.  From  mesial  to  distal;  as,  the  mesio-distal  diameter  of  the 
lower  first  molar. 

Mesio-distallt.  a  direction  from  the  mesial  toward  the  distal  following  the 
curve  of  the  dental  arch. 

Mesio-distal  plane.    A  contraction  of  axio-mesio-distal  plane  (q.  v.). 

Mesio-incisal  angle.  The  angle  formed  by  the  junction  of  the  mesial  surface 
and  cutting  edge,  or  incisal  surface,  in  the  incisors  and  cuspids. 

Mesio-labial  angle.  The  angle  formed  by  the  union  of  the  mesial  and  labial 
surfaces  of  the  incisors  and  cuspids. 

Mesio-lingual  angle.  The  angle  formed  by  the  union  of  the  mesial  and  lingual 
surfaces  of  the  teeth. 

MESlo-LlNGUAi  GROOVE.  A  developmental  groove  running  from  the  mesial  sur- 
face diagonally  to  the  lingual  surface  in  upper  first  molars  that  have  the  fifth  cusp. 

Mesio-linguo-occlusal  ANGLE.  The  angle  formed  by  the  junction  of  the  mesial, 
lingual  and  occlusal  surfaces  of  the  bicuspids  and  molars  at  a  point. 

Mesio-occlusal  ANGLE.  The  angle  formed  by  the  union  of  the  mesial  and 
occlusal  surfaces  of  the  bicuspids  and  molars.  It  forms  the  mesial  marginal  ridge 
of  the  occlusal  surfaces. 

Metabolism.  The  sum  of  the  nutritive  processes  in  cells  and  organs  of  living 
things.  It  includes  the  vital  phenomena  of  absorption,  assimilation  and  nutrition 
on  the  one  hand  and  the  biochemical  changes  in  the  liberation  of  waste  products  on 
the  other. 

Micrometer.  An  instrument  for  the  measurement  of  very  minute  divisions  of 
space.  They  are  made  to  measure  divisions  of  one  thousandth  or  one  ten-thousandth 
of  an  inch;    one  hundredth,  or  one  thousandth  of  a  millimeter,  etc. 

MiCROPHOTOGRAPH.  A  photograph  of  microscopic  size  made  of  any  ordinary 
object.     In  this  the  image  produced  is  very  much  smaller  than  the  object. 

Mobile.  Having  wide  movements,  as  mobile  features,  mobile  lips,  etc.  The 
features  of  a  person  may  be  very  mobile  so  that  the  teeth  come  prominently  into  view 
in  laughing  and  speaking.     This  does  not  mean  prominent  teeth.     See  Immobile. 


GIjOSSAEY    of    technical    terms    AJSl)    PHKASES.  297 

Mucin.  An  albuminoid  substance,  the  chief  constitufint  of  mucus.  It  is  insolu- 
ble in  water  and  is  precipitated  by  alcohol,  alum  and  acids.  Mucin  is  present  in 
saliva,  mucous  secretions,  the  bile,  and  in  certain  cysts.     Dorland. 

Mucus.  A  thick  viscid  secretion  from  the  raucous  follicles  situated  in  the  mucoiis 
membranes  of  the  mouth.  A  somewhat  similar  mucus  is  found  on  other  mucous 
membranes. 

Names  of  angles  of  cavities  and  sets  of  cavity  angles.  The  first  set  of  line 
angles  is  formed  by  the  junction  of  tho  surrounding  walls  of  a  cavity  with  each 
other.  In  occlusal  cavities  these  will  be  the  mesio-buceal,  mesio-lingual,  disto-buccal 
and  distolingual  angles.  In  simple  mesial  or  distal  cavities  they  will  be  the  bucco- 
gingival,  linguo-gingival,  buccoocclusal  and  liuguoocelusal  angles.  In  simple  buccal 
or  lingual  cavities,  they  will  be  the  mesio-gingival,  disto-gingival,  mesio-occlusal  and 
disto-occlusal  angles. 

A  second  set  of  line  angles  will  be  formed  in  occlusal  cavities  by  the  junction 
of  the  surrounding  walls  with  the  pulpal  wall.  And  in  mesial,  distal,  buccal  and 
lingual  cavities  by  the  junction  of  the  surrounding  walls  with  the  axial  wall.  In 
occlusal  cavities  these  will  be  the  pulpo-mesial,  pulpo-buccal,  pulpo-distal  and  pulpo- 
lingual  angles.  In  simple  mesial  or  distal  cavities  these  will  be  the  axiogingival, 
axio-buccal,  axio-occlusal  and  axio-lingual  angles.  In  buccal  or  lingual  cavities  these 
will  be  the  axio-gingival,  axio-distal,  axio-occlusal  and  axio-mesial  angles. 

The  point  angles  in  occlusal  cavities  will  be  the  pulpo-mesio-buccal,  pulpo-disto- 
buccal,  pulpo-mesio -Ungual  and  pulpo-disto-lingual.  In  simple  mesial  and  distal 
cavities  these  will  be  the  axio-bueeo-gingival,  axio-linguo-gingival,  axio-bucco-occlusal 
and  axio-linguo-occlusal  angles.  In  simple  buccal  or  lingual  cavities  these  wiU  be 
the  axio-mesio-gingival,  axio-disto-gingival,  axio-mesio-occlusal  and  axio-disto-occlusal 
angles. 

In  any  case  in  which  a  mesial,  distal,  buccal  or  lingual  cavity  is  cut  into  the 
occlusal  surface  forming  a  complex  cavity,  the  angles  toward  the  occlusal  are  missing 
and  the  angles  that  are  formed  in  the  step  portion  will  be  named  as  in  simple  occlusal 
cavities.  In  this  case,  and  in  any  of  these  cavities,  the  junction  of  the  axial  and 
pulpal  walls  will  form  the  axio-pulpal  line  angle.  In  mesio-  or  disto-occlusal  cavities 
the  junction  of  this  with  the  buccal  and  lingual  walls  will  form  the  axio-pulpo-buccal 
and  the  axio-pulpo-lingual  point  angles.  In  bucco-  or  linguo-occlusal  cavities  the 
axio-pulpo-mesial  and  axio-pulpo-distal  point  angles  are  formed  in  a  similar  way. 
See  Note  on  Compound  Words  following  definition  of  Angle. 

In  incisor  or  cuspid  mesial  or  distal  cavities,  the  iirst  set  of  line  angles  will  con- 
sist of  the  labio-gingival,  lingiio-gingival  and  ineisal  angles.  The  second  set  will  be 
the  axio-labial,  axio-gingival  and  axio-Ungiial  angles.  The  point  angles  will  be  the 
axio-labio-gingival,  axio-linguo-gingival  and  the  axio-incisal.  This  latter  is  usually 
called  the  ineisal  angle  and  is  regarded  as  an  exception  to  the  rules  of  naming  angles 
of  cavities. 

In  incisor  or  cuspid  labial  or  lingual  cavities  the  first  set  of  line  angles  will  be 
the  mesio-gingival,  disto-gingival,  mesio-incisal  and  disto-incisal.  The  second  set 
will  be  the  axio-mesial,  axio-distal,  axio-gingival  and  axio-iueisal. 

The  point  angles  will  be  the  axio-mesio-gingival,  axio-disto-gingival,  axio-mesio- 
incisal,  axio-disto-incisal. 

Names  op  cavity  makgins.  Cavity  margins  take  the  names  of  the  margins  of 
the  surfaces  of  the  teeth  in  which  they  occur;  or  each  cavity  margin  takes  the 
name  of  the  cavity  wall  of  which  it  forms  the  margin  or  cavo-surface  angle.  There- 
fore, cavity  walls,  cavity  margins,  cavo-surface  angles  and  margins  of  surfaces  of 
teeth,  take  the  same  names,  the  difference  being  only  the  specification  as  to  which 
they  belong. 

Names  of  cavo-surface  angles  of  cavities.  Each  cavo-surface  angle  of  a 
cavity  takes  the  name  of  the  caWty  wall  to  which  it  belongs.  See  Names  of  Cavity 
Margins. 

Names  of  margins  of  surfaces  of  the  teeth.  These  take  the  names  of  the 
surfaces  of  the  teeth  toward  which  they  are  placed.  In  the  bicuspids  and  molars 
these  are  the  mesial,  buccal,  distal  and  lingual  margins  of  occlusal  surfaces;  the 
mesial,  occlusal,  distal  and  gingival  margins  of  buccal  and  lingual  surfaces;  the 
buccal,   occlusal,   lingual   and   gingival   margins   of  mesial   and   distal   surfaces.      In 


298  PATHOLOGY    OF    THE    HABD    TISSUES    OF    THE    TEETH. 

the  incisors  and  cuspids  these  are  the  mesial,  incisal,  distal  and  gingival  margins  of 
labial  and  lingual  surfaces.  Proximal  surfaces  of  the  incisors,  because  of  their 
triangular  form,  have  but  three  margins:  the  labial,  gingival  and  lingual.  The 
incisal  surface  or  edge  is  not  supposed  to  have  margins  ordinarily  requiring  names, 
but  in  case  of  any  necessity,  especially  in  cases  of  considerable  abrasion,  the  margins 
would  be  named  on  the  same  plan  as  the  above. 

Naming  op  cavities,  rule  for.    See  Eules  for  Naming  Cavities. 

Naming  of  cavity  walls,  rules  for.    See  Eules  for  Naming  Cavity  Walls. 

Naysmith  's  membrane,  a  membrane-like  glaze  covering  the  enamel  of  a  tooth, 
discovered  by  Naysmith.  It  may  be  parted  from  the  enamel  by  careful  digestion  in 
weak  solutions  of  acids.  It  is  worn  away  from  the  parts  of  the  teeth  exposed  to 
friction  very  early  in  life. 

Neck.  That  portion  of  the  tooth  which  forms  the  junction  of  the  crown  and 
root. 

Necsosis.    Local  death  of  a  part  of  a  tissue,  especially  of  bone,  in  a  mass. 
Necrotic.    Pertaining  to  necrosis  or  local  death  of  tissue,  particularly  of  bone. 

Nerve.  ' '  Nerve  of  a  tooth. ' '  Once  a  common  name  for  the  dental  pulp.  Obso- 
lete. 

Neuritis.     Inflammation  of  a  nerve,  or  of  nerves. 
Neurosis.    A  functional  disease  of  the  nerves. 

Nib.  That  part  of  a  working  end  of  a  plugger  point  that  corresponds  to  the 
blade  of  an  excavator. 

Nomenclature.  A  system  of  naming  things  or  acts.  Each  profession  or  busi- 
ness has  its  own  system  of  naming  things  or  acts  pertaining  to  it. 

Nomenclature  of  cavities.  In  dentistry,  a  system  of  nomenclature  applied  to 
cavities  in  teeth.  Under  this  term  is  included  aU  of  the  names  of  cavities.  Names 
of  cavity  walls,  of  angles  of  cavities  and  their  terms  of  cavity  description,  together 
with  the  rules  of  their  use. 

Non-cohesive  gold.  Gold  in  the  form  of  foil  or  crystals  in  which  the  welding 
property  is  obscured,  usually  by  the  condensation  of  some  gaseous  substance  upon 
it,  or  a  film  of  a  salt  from  the  union  of  two  or  more  gases. 

Oblique  ridge.  A  ridge  running  obliquely  across  the  occlusal  surface  of  the 
upper  molars.  It  is  formed  by  the  union  of  the  triangular  ridge  of  the  disto-buccal 
cusp  with  the  distal  portion  of  the  ridge  forming  the  mesio-lingual  cusp. 

Occlude.    To  shut;    to  close. 

Occlusal,  a.  The  surfaces  of  the  teeth  which  come  together  when  the  jaws  are 
closed,  are  called  occlusal  surfaces. 

Occlusal  cavities.  Cavities  formed  by  decay  beginning  in  the  occlusal  sur- 
faces in  the  bicuspids  and  molars.     They  are  all  pit  or  fissure  cavities. 

Occlusal  surface,  n.  That  surface  of  a  bicuspid  or  molar  tooth  that  makes 
contact  with  a  tooth  of  the  opposite  jaw  when  the  mouth  is  closed. 

Occlusion.  The  act  of  closing  or  shutting.  The  closing  of  the  teeth.  ' '  Correct 
occlusion,"  the  normal  contact  of  the  teeth  of  each  jaw  when  the  mouth  is  closed. 

Odontoblasts.  A  layer  of  oblong  cells  that  line  the  pulp  chambers  of  the  teeth. 
They  are  the  dentin  forming  cells.  Processes  from  the  odontoblasts  pass  through 
the  dentinal  canals  to  the  dento-enamel  junction,  and  to  the  junction  of  the  dentin 
and  cementum.     See  Fibrils  of  Tomes. 

0D0NT0CLA.STS.  The  giant  cells  which  are  the  active  agents  in  the  absorption  of 
the  roots  of  the  deciduous  teeth. 


GLOSSARY    OF    TECHNICAL    TERMS    AND    PHRASES.  299 

"Onetwo-tiikee. "  "1-2-3."  A  local  antiseptic  composed  of  oil  of  cassia,  1 
part,  carbolic  aciil  (melted  crystals)  2  parts,  oil  of  wiiitergreen,  3  parts.  The  oila 
should  be  mixed  and  the  melted  crystals  of  carbolic  acid  added. 

Operative  dentistry.  Those  operations  upon  the  natural  teeth  and  the  soft 
parts  connected  with  tliem  that  are  usually  performed  by  the  dentist  for  their  con- 
servation, or  cure  of  disease.  It  includes  the  employment  of  such  drugs  or  remedial 
agents  as  may  be  necessary. 

Oral.    Pertaining  to  the  mouth,  as  Oral  Surgery. 

Order  names,  of  instruments.  A  name  given  to  any  group  of  instruments  vphich 
designates  their  use,  as  excavators,  pluggers,  etc. 

Ordinaries,  as  applied  to  cutting  instruments.  The  usual  hatchets  and  hoes 
used  by  dentists  in  excavating  cavities. 

Orthodontia.  The  moving  of  malposed  teeth  to  correct  positions.  The  art  of 
regulating  the  position  of  malposed  teeth. 

Osmosis.    The  act  of  the  passage  of  soluble  salts  through  animal  membranes. 

Osteoblasts.    The  cells  which  form  bone. 

Osteoclasts.     The  giant  cells  which  effect  the  absorption  and  removal  of  bone. 

Outline  form.  In  cavity  preparation;  the  form  of  the  area  of  tooth  surface 
included  in  the  prepared  cavity. 

Outward  inclination.  Said  of  cavity  walls  when  they  diverge  from  each  other 
In  approaching  the  surface  of  the  tooth. 

Packer.    See  Plugger. 

Palatal.  Pertaining  to  or  directed  toward  the  palate.  "Palatal  surfaces  of 
the  teeth."    Obsolete. 

Palm-and-thumb  grasp.  The  instrument  shaft  is  grasped  in  the  palm  of  the 
hand  and  the  working  point  brought  into  opposition  to  the  thumb  as  a  counteracting 
force.  Used  in  positions  in  which  an  instrument  can  be  applied  to  one  side  or  portion 
of  a  tooth,  or  other  object,  while  the  thumb  of  the  same  hand  is  rested  upon  it,  or 
upon  adjacent  teeth.     See  Figure  29,  Vol.  2. 

Palm  thrust  grasp.  The  end  of  the  instrument  handle  is  placed  in  the  hollow 
of  the  palm  of  the  hand  and  grasped  by  the  fingers.  Used  for  making  a  powerful 
thrust.    See  Figure  30,  Vol.  2. 

Pen  grasp.  A  grasp  of  dental  instruments  closely  resembling  the  usual  grasp 
of  a  pen  used  in  writing.  In  the  use  of  dental  instruments  the  pulps  of  the  thumb, 
first  and  second  fingers  should  be  on  the  instrument  shaft.     See  Figure  26,  Vol.  2. 

Pericementum.  The  membrane  covering  the  cementum  of  the  roots  of  teeth. 
See  Peridental  Membrane. 

Peridental  membrane.  The  membrane  surrounding  the  root  of  a  tooth  and 
forming  its  attachment  to  the  walls  of  its  alveolus.  It  is  composed  of  fibers  which 
are  built  into  the  cementum  on  the  one  side  and  into  the  bone  on  the  other.  Among 
these  fibers  there  is  an  abundant  network  of  blood  vessels,  nerves  and  cellular  ele- 
ments. 

Periosteal  bone.  Bone  laid  down  by  the  osteoblasts  of  the  periosteum  as  dis- 
tingushed  from  Haversian  systems  bone. 

Permanent  teeth.  The  teeth  of  adult  age  as  distinguished  from  the  temporary, 
or  deciduous  teeth. 

Permanent  teeth,  childhood  period  op.  The  period  from  the  first  appearance 
of  the  permanent  teeth  until  their  roots  are  fully  completed,  except  the  third  molars. 
See  Figure  187,  Vol.  1. 


300  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

Peksoxal  equation.  When  one  person  accomplishes  any  certain  result,  which 
another  fails,  or  in  part  fails  to  do,  and  the  differences  in  opportunity  and  method 
seem  inexplicable,  the  difference  is  said  to  be  a  personal  equation.  As  these  differ- 
ences are  being  occasionally  explained  by  more  acute  observation  or  by  physical  meas- 
urements, they  are  found  to  be  due  to  personal  physical  conditions,  or  to  differences 
in  mental  grasp  of  requirements. 

Phagodynamometer.  An  instrument  by  which  the  force  required  in  crushing 
different  examples  of  foodstuffs  is  determined.     See  Figure  166,  Vol.  I. 

Photomicrograph.  A  photograph  of  a  tissue  or  other  prepared  object  taken  by 
transmitted  light  with  a  microscopic  lens.  This  should  be  distinguished  from  a 
photograph  made  by  reflected  light  by  a  microscopic  lens  of  low  power  such  as  the 
photograph  of  a  tooth  in  which  the  object  is  enlarged  from  two  to  eight  or  ten  diam- 
eters. Photomicrographs  may  have  an  enlargement  anywhere  from  two  or  three 
diameters  to  a  thousand  or  more. 

Pit.  a  sharp,  pointed  depression  in  the  enamel.  Pits  occur  mostly  where  several 
developmental  grooves  join;  as  in  the  occlusal  surfaces  of  the  molars,  at  the  endings 
of  the  buccal  grooves  on  the  buccal  surfaces  of  the  molars;  occasionally  in  the  lin- 
gual surfaces  of  the  incisors. 

Pit  cavities.  Those  cavities  that  begin  in  pits.  Cavities  formed  by  decay  that 
begins  in  pits  of  anj'  kind  or  in  any  position.  See  Figures  68,  69,  70,  71,  75,  76,  77, 
Vol.  1. 

Planes  of  the  teeth.  Any  planes  cutting  the  teeth  in  definite  directions,  as 
the  axial  plane,  horizontal  plane,  etc. 

Plaque.  A  flat  circumscribed  area  or  plate ;  a  flat  plate  made  up  of  a  colony 
of  microorganisms  in  zooglea  form,  clinging  to  enamel  of  the  teeth. 

Plastics.  Materials  like  cements,  gutta-percha  and  amalgam  for  filling  cavities 
in  teeth;   a  material  for  any  purpose  that  may  be  easily  modeled  and  built  into  form. 

Plug.  A  filling  placed  in  a  prepared  cavity  in  a  tooth  is  often  called  a  plug. 
In  England  the  word  stopping  is  used.     See  Pilling. 

Plugger.  An  instrument  for  condensing  gold  or  other  material  in  ca\'ities  in 
teeth.     These  are  sometimes  called  packers  or  packing  instruments. 

Plugging  instruments.    See  Plugger. 

Point  angles.  Of  the  teeth:  Those  angles  formed  by  the  junction  of  the 
angles  of  three  surfaces  at  a  point;  as  the  disto-bucco-occlusal  angle,  the  mesio- 
bucco-occlusal  angle,  etc.  Of  cavities:  Those  angles  formed  by  the  junction  of 
three  cavity  walls  at  a  point;   as  the  axio-bucco-gingival  angle. 

Point  of  proximal  contact.  The  point  at  which  the  proximal  surface  of  a 
tooth  touches  the  proximal  surface  of  a  neighboring  tooth.     See  Contact  Point. 

Positions  at  the  chair.  Those  positions  which  the  dentist  should  assume  in 
doing  dental  operations.  A  systematized  nomenclature  of  positions  at  the  chair. 
See  Figures  34-45,  inclusive,  Vol.  2. 

Preparation  op  cavities.  Those  operations  required  in  forming  cavities  in 
teeth  for  the  reception  of  fillings. 

Prognathism.    Abnormal  protrusion  of  one  or  both  jaws. 

Prognathous.     Having  projecting  jaws. 

Prognosis.     A  prediction  as  to  the  progress  and  result  of  a  disease. 

Prophylactic.  Tending  to  prevent  disease;  guarding  against  disease.  A  medi- 
cine or  preparation  which  defends  or  protects  against  disease.  Something  applied  to 
healthy  tissue  to  prevent  disease. 


GLOSSARY    OF    TJiOHNICAL.   TEKMS    AND    PHKASES.  301 

Prophylaxis.  Preventive  medicine.  Oral  prophylaxis:  Preventive  measures 
against  diseases  of  the  mouth. 

Proximal.    Latin;    proximus,  near;    propior,  nearer;    propious,  next  or  nearest. 

Note.  This  is  the  oldest  fonn  of  the  word  in  the  Latin.  In  use  in  the  Latin,  proprius  became 
obsolete;  in  time  the  word  went  through  many  changes  and  proximns  was  used  as  the  superlative 
adjective,  moaning  nearest  —  next  in  line  before  or  after.  But  in  following  the  word  through  the 
time  of  the  active  use  of  the  Latin  language,  we  find  it  used  in  a  variety  of  subjects,  as:  Time, 
next  day,  next  month,  or  next  year.  Relationship,  next  of  kin,  next  neighbor.  Of  things,  next  house. 
Of  a  series,  the  next  preceding  or  following,  etc.  Quotations  from  Harpers'  Latin  Dictionary.  Proxi- 
mus: of  place,  nearer,  nigher;  of  time,  nearer,  later,  more  recent;  of  relationship,  nearer,  more 
nearly  related  ;  of  resemblance,  more  nearly  resembling,  more  like ;  of  relation  or  connection,  more 
nearly  related,  of  greater  import,  closer,  more  intimate. 

In  later  composition.  Proximus:  The  nearest,  next,  one's  nearest  neighbor,  close  by,  next  door. 
The  next  preceding  or  following ;  the  previous,  the  last ;  the  next,  the  following,  ensuing ;  time, 
recently,  last  of  all,  next  day,  ne.xt  month,  next  year,  etc. 

Webster  defines  proximal  thus:  "Toward  or  nearest,  as  to  a  body  or  center  of  motion  or  depend- 
cnce.  Proximate.  (Biol.)  (a)  Situated  near  the  point  of  attachment  or  origin;  as  the  proximal 
part  of  a  limb,  twig  or  leaf,  (b)  Of  or  pertaining  to  that  which  is  proximal ;  as  the  proximal  bones 
of  a  limb.     Opposed  to  distal." 

Dentistry:  That  surface  of  a  tooth  that  is  toward,  nearest,  or  in  contact  with 
another  tooth  to  the  mesial  or  distal  as  the  teeth  are  arranged  in  the  arch. 

Note.  The  word  proximal  has  been  much  used  in  anatomy  and  botany  as  the  opposite  of  distal, 
or  as  next  to  a  thing  understood  ;  as  the  central  body,  or  trunk.  The  proximal  end  of  a  bone  is  that 
nearest  the  central  line  of  the  body.  The  distal  end,  that  which  is  farthest  from  the  central  line  of 
the  bodv.  In  botany,  it  is  used  in  a  similar  sense,  the  portion  of  the  limb  of  a  tree  nearest  the 
trunk  is'  the  proximal  portion.  It  is  used  in  the  same  manner  in  the  description  of  twigs  and  leaves. 
It  is  also  used  in  the  adverbial  form  (proximally)  to  express  direction  along  a  limb,  twig  or  leaf. 
This  meaning  has  been  acquired  in  recent  time  and  is  not  quite  in  harmony  with  the  Latin  use  of  the 
adjectives  of  proximarc,  near  to  or  next  to  anything  or  object  preceding  or  following. 

John  Tomes  gave  us  the  word  mesial  as  the  opposite  to  distal  instead  of  proximal  for  nammg 
surfaces  of  the  teeth.  In  this  use,  mesial  designates  the  surface  of  a  tooth  toward  the  median  line, 
and  distal  the  surface  farthest  from  the  median  line.  Much  difficulty  was  ex-perienced  by  many 
persons  in  the  use  of  these  words  until  the  definition  of  their  meaning,  when  applied  to  the  surfaces 
of  the  teeth,  was  extended  by  the  additional  words  italicized  in  the  following  definition.  By  mesial 
is  meant  those  surfaces  of  the  teeth  which,  as  Ihey  stand  in  the  arch,  and  following  its  curve,  are 
toward  the  median  line.  This  seemed  satisfactory  and  the  use  of  the  words,  mesial  and  distal,  in 
place  of  proximal  and  distal,  has  become  fully  established.  But  there  was  a  real  necessity  for  a  word 
that  would  designate  collectively  the  surfaces  defined  as  mesial  and  distal  and  the  usage  of  many 
persons  in  the  dental  profession  has  clung  tenaciously  to  the  term  proximal,  as  meaning  next,  or  next 
to,  which  is  really  its  Latin  signification,  in  spite  of  the  fact  that  it  has  been  used  in  a  special 
sense  in  biology  as  next  to  the  central  part  or  point  of  origin,  understood,  but  generally  not  men- 
tioned except  in  definitions.  In  dentistry  its  use  is  nearer  the  original  Latin  meaning  of  the  words 
from  which  the  recent  English  adjective  form  has  been  derived. 

Harris,  in  his  writing,  seems  to  have  used  proximal,  proximate,  appro.ximate,  approach,  approach- 
ing, etc.,  in  phrases  describing  proximal  surfaces,  but  evidently  did  not  regard  any  of  these  as  assuming 
the  force  of  nomenclature  words,  for  he  did  not  Include  any  of  them  in  his  dictionary  of  terms. 

In  the  literature  pertaining  to  this,  articles  will  be  foimd  in  the  Dental  Cosmos,  1880,  page  84 
and  page  139;  1890,  page  325;  which  show  in  part  one  of  the  reasons  for  the  confusion  that  still 
exists  because  of  the  introduction  of  the  awkward  term,  approximal.  Personally,  I  made  objection 
then  to  the  use  of  this  term,  foreseeing  that  it  would  give  rise  to  much  difficulty  in  compounding 
terms  which  were  sure  to  come  with  advances  in  dental  nomenclature.  In  conversation  with  Dr. 
James  W.  WTiite,  who  was  then  editor  of  the  Dental  Cosmos,  I  obtained  the  history  of  this  effort  to 
substitute  the  word  approximal.  After  a  study  of  this.  Dr.  White  decided  to  favor  this  word  and 
applied  to  several  persons  who  were  then  engaged  in  the  revision  of  dictionaries,  asking  that  the 
word  be  in.serted  with  a  definition  he  had  written.  This  was  not  granted,  because  there  was  no  litera- 
ture showing  the  use  of  the  word.  Dr.  White  then  wrote  one  or  more  articles  using  the  word,  caused 
them  to  be  printed  and  presented  them  as  evidence  of  its  use  in  the  literature.  In  this  way  he  suc- 
ceeded in  having  it  inserted  in  Thomas'  Medical  Dictionary.  It  seems  not  to  have  been  placed  in  other 
dictionaries.  Dr.  White  should  be  credited  with  an  earnest  endeavor  to  Improve  dental  nomenclature. 
I  still  think  his  choice  of  this  word  unfortunate. 

•The  word  is  obnoxious  because  of  the  addition  of  the  unnecessary  syllable,  ap,  and  particularly 
so  in  such  compounds  as  interproximal  gum  tissue,  interapproximal  becomes  cumbersome.  "The  fact  is, 
many  in  the  profession  have  held  to  the  use  of  the  word,  proximal,  in  spite  of  every  effort  to  displace 
it.  I  understood  the  full  meaning  of  the  incongruity  of  the  use  of  the  word  proximal  after  its  use 
in  a  changed  signification  from  the  Latin  proximus,  from  next  in  line  before  or  after,  to  next  to  the 
central  tnmk.  I  expressed  this  clearly  in  my  report  on  dental  nomenclature  to  the  Columbian  Dental 
Congress  in  1893,  and  I  continued  the  use  of  the  word  proximate,  which  had  formerly  been  used  by 
the  Dental  Cosmos.  The  editor  of  the  Dental  Cosmos,  after  making  this  choice,  in  editing  articles 
for  its  pages  changed  all  words  used  by  writers  and  speakers  to  designate  these  surfaces  to  approximal. 
Many  others  have  supported  this  effort,  and  yet  the  word  proximal  has  not  been  displaced.  This  evi- 
dent and  persistent  disposition  of  the  dental  profession  to  use  the  word,  proximal,  renders  it  the  better 
word  in  spite  of  its  use  in  a  different  sense  from  the  original  Latin  adjective  in  biology.  The  boot- 
black makes  a  noun  out  of  a  verb  —  "  Have  a  shine,  sir,"  and  the  philologist  must  submit.  Therefore, 
in  this  book  the  word  proximal  has  been  used. 

ProximaI/  CAVITIES.  Cavities  beginning  in  the  proximal  surfaces  of  the  teeth. 
As  both  mesial  and  distal  cavities  are  included  under  this  term,  it  is  used  only  when 
it  is  intended  to  include  mesial  and  distal  cavities  collectively,  or  when  the  position, 
mesial  or  distal,  is  not  determined,  or  mentioned;    as  proximal  cavities  in  the  incisors. 


302  PATHOLOGY    OP    THE    HAED   TISSUES   OF    THE    TEETH. 

Proximal  contact.  The  contact,  or  touching,  of  the  proximal  surfaces  of 
neighboring  teeth. 

Peoximal  sdeface.  The  surface  of  a  tooth  which  lies  next  to  another  tooth, 
to  the  mesial  or  to  the  distal. 

Proximate.    Formerly  used  instead  of  proximal.    See  Proximal. 

Proximating.  a  tooth  or  portion  of  the  surface  of  a  tooth  making  near 
approach  to  another  tooth  or  portion  of  the  surface  of  another  tooth. 

Proximation.  The  near  approach,  or  contact,  of  the  proximal  surfaces  of  the 
teeth. 

Pulp.  The  soft  tissue  that  fills  the  pulp  chambers  and  root  canals  of  the  teeth. 
It  is  the  formative  organ  of  the  dentin. 

Pulp  canal.  The  central  opening  lengthwise  in  the  root  of  a  tooth  leading 
from  the  pulp  chamber  or  bulb  of  the  pulp  in  the  crown  portion  of  a  tooth  to  the 
apical  end  of  the  root.     Syn.  Root  Canal. 

Pulp  chamber.  The  central  opening  in  the  dentin  of  the  crown  portion  of  a 
tooth  which  is  occupied  by  the  pulp  of  the  tooth.  In  the  double  and  triple-rooted 
teeth,  the  pulp  chambers  are  very  distinct  from  the  root  canals,  but  in  teeth  having 
but  one  root  the  pulp  chamber  is  not  distinctly  divided  from  the  root  canal. 

Pulpitis.    Inflammation  of  the  dental  pulp. 

Putrefaction.  Putrefactive  fermentation.  Decomposition  with  a  foul  odor 
of  animal  or  vegetable  matter,  effected  by  the  action  of  microorganisms.  The  true 
putrefactions  occur  only  when  oxygen  is  excluded,  but  decompositions  of  a  somewhat 
similar  nature  occur  in  the  presence  of  oxygen. 

Putrescent.    A  state  of  decomposition  with  emission  of  foul  odor. 

Pyogenic.  Said  of  a  microorganism  that  generates  pus,  or  causes  pus  forma- 
tion. The  staphylococcus  albus,  staphylococcus  aureus,  streptococcus  longus,  etc.,  are 
pus-generating  microorganisms.     They  are  therefore  pyogenic. 

Pyorrhea.  A  flow  of  pus.  ' '  Pyorrhea  alveolaris. ' '  A  flow  of  pus  from  the 
alveoli  of  the  teeth. 

Quadrangle.  In  instrument  nomenclature  designates  an  instrument  mth  four 
angles  or  curves  in  the  shank. 

Range.  Sizes  of  instruments  or  angles  of  their  blades  on  definite  comparative 
gradations. 

Ee.     In  the  matter  of,  referring  to.     Murray. 

Resistance  form.  In  cavity  preparation;  the  shape  given  to  the  internal  parts 
of  a  cavity  to  afford  such  a  seat  for  the  filling  as  will  best  enable  it  to  withstand 
great  stress  without  movement. 

Besoeption.  The  act  of  absorbing  again.  There  has  been  an  effort  to  use  this 
word  in  a  special  sense,  or  to  apply  it  to  special  kinds  of  absorptions,  which  seems 
not  to  have  been  very  successful.  Some  writers  use  it  in  speaking  of  the  absorption 
of  the  roots  of  the  deciduous  teeth. 

Retention  form.  In  cavity  preparation;  the  form  of  the  internal  parts  of  a 
cavity  provided  to  prevent  the  displacement  of  the  filling  by  force. 

Retzius,  calcificvtion  lines  of.     See  Lines  of  Accretion. 

Ridge.    A  long-shaped  elevation  on  the  surface  of  a  tooth. 

Boot.  That  portion  of  the  tooth  that  is  fixed  in  the  alveolus,  or  socket,  and  is 
covered  with  cementum. 


GLOSSARY    OF    TECHNICAL.   TEEMS    AND    PHRASES.  303 

Root  canal.  Th(!  oponing  through  the  center  of  the  long  axis  of  the  root  of  a 
tooth  from  the  erown  to  the  apex,  which  under  normal  conditions  contains  the  root 
portion  of  the  dental  pulp.     Sjn.  Pulp  Canal. 

Ropy  saliva.  Saliva  that  may  be  drawn  out  in  threads  by  touching  it  with  the 
finger  and  pulling  away.    See  Viscous  Saliva. 

Round  bur.    A  bur,  the  head  or  cutting  part  of  which  is  spherical  in  form. 

Rubber  dam.  A  thin  sheet  of  very  elastic  rubber  used  for  keeping  the  teeth, 
and  especially  cavities  in  the  teeth,  dry  and  clean  while  performing  such  operations 
as  filling,  removing  pulps,  filling  pulp  canals,  etc. 

RlTBBER  DAM  CLAMP.  An  instrument  made  to  set  on  teeth  over  the  rubber  dam  to 
hold  it  in  place,  or  over  which  the  rubber  dam  may  be  thrown.  It  is  made  of  spring 
steel,  and,  in  applying  it,  it  is  opened  with  a  special  forceps,  placed  in  position  and 
allowed  to  close  on  the  tooth  with  the  force  of  its  spring. 

Rubber  dam  grasps.  The  forms  of  grasp  of  the  rubber  dam  best  suited  to  its 
application  to  teeth  in  different  parts  of  the  mouth.  Of  these  there  are  five,  numbered 
first,  second,  etc.     See  Figures  66-83,  inclusive,  Vol.  2. 

Rugae.     A  series  of  irregular  ridges  in  the  roof  of  the  mouth. 

Rules  for  naming  angles  of  cavities.  (1)  Angles  of  cavities  are  named  by 
uniting  the  names  of  the  walls  which  meet  to  fonn  the  angles.  (2)  A  line  angle  is 
formed  by  the  meeting  of  two  walls,  as  the  axio-gingival  line  angle,  at  the  junction 
of  the  axial  and  gingival  walls.  (3)  A  point  angle  is  formed  by  the  meeting  of  three 
walls,  as  the  axio-gingivo-bucoal  point  angle  at  the  junction  of  the  axial,  gingival  and 
buccal  walls.  These  angles  may  be  either  sliarp  or  smoothly  rounded,  but  are  named 
as  if  they  were  definite  angles.     See  Names  of  Angles  of  Cavities. 

Rules  for  naming  cavities.  (1)  Cavities  in  teeth  take  the  names  of  the  sur- 
faces of  the  teeth  in  which  they  occur;  as  occlusal  cavity,  mesial  cavity,  etc.  (2) 
When,  from  extension  of  decay  or  by  cutting  in  cavity  preparation,  a  second  surface 
becomes  involved,  or  two  decays  beginning  in  separate  surfaces  have  become  united, 
the  names  of  the  two  or  more  surfaces  involved  are  united  in  naming  the  cavity;  as 
mesio-occlusal  cavity,  mesio-occluso-distal  cavity.     See  Figure  3,  Vol.  2. 

Rules  for  naming  cavity  walls.  (1)  The  surrounding  walls  of  a  cavity  take 
the  names  of  those  surfaces  of  the  teeth  adjoining  the  surface  decayed  toward  which 
they  are  placed;  as,  mesial  wall,  buccal  wall,  etc.,  of  an  occlusal  cavity.  See  Figures 
1,  3,  Vol.  2. 

(2)  That  wall  of  a  cavity  which  is  to  the  occlusal  of  the  pulp,  and  in  the  hori- 
zontal plane,  or  at  right  angles  to  the  long  axis  of  the  tooth,  is  called  the  pulpal  wall. 
See  Figures  1,  3,  Vol.  2.  In  case  the  pulp  of  the  tooth  is  removed  and  the  cavity 
thus  extended  to  the  floor  of  the  pulp  chamber,  it  is  called  the  sub-pulpal  wall. 

(3)  That  wall  of  a  cavity  iu  an  axial  surface  of  a  tooth  that  covers  the  pulp 
is  called  the  axial  wall.  See  Figures  3,  7,  Vol.  2.  If  the  pulp  of  the  tooth  is  removed, 
the  cavity  is  extended  to  include  the  pulp  chamber,  the  wall  takes  the  name  of  the 
wall  of  the  pulp  chamber;    as,  the  distal  wall,  in  a  mesial  cavity. 

(4)  When  one  of  the  waUs  of  a  cavity  is  missing  by  extension  of  decay,  or  by 
extension  by  cutting  in  the  preparation  of  a  cavity  for  filling,  so  as  to  involve  another 
surface  of  the  tooth,  a  complex  cavity  is  formed,  and  the  remaining  walls  extend  to 
the  new  surface  involved. 

Saliva.  The  fluid  poured  into  the  mouth  from  the  salivary  glands.  Usually 
when  the  saliva  is  spoken  of  without  restricted  definition,  the  mixed  fluid  as  found 
in  the  mouth  is  meant.  It  is  composed  of  the  saliva  proper  from  the  parotid,  sub- 
maxillary, sub-lingual  and  other  smaller  glands,  and  the  secretion  of  the  mucous 
follicles,  which  open  into  the  mouth. 

Scaler.     A  dental  instrument  for  removing  calculus  from  the  teeth. 

Scaling.  The  removal  by  special  instruments  of  scale-like  depositis  of  calculus 
from  the  crowns  and  roots  of  the  teeth.     A  curetting  process. 

Senile.    Pertaining  to  old  age. 

Sensitiveness.  The  quality  or  capability  of  being  sensitive  to  painful  impres- 
sion. 


304  PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 

Separator.  An  instrumeut  or  mechanical  appliance  designed  for  forcibly  sep- 
arating teeth  for  obtaining  space  between  proximal  surfaces  for  examinations,  exca- 
vation of  cavities,  finishing  fillings,  etc. 

Sepsin.  a  soluble  poison  (ptomain)  present  in  putrid  blood,  flesh,  or  in  proteid 
compounds. 

Sepsis.    Poisoning  of  the  system  by  the  introduction  of  sepsin  into  the  blood. 

Septal  gingivae.    That  portion  of  the  gingivae  in  the  interproximal  space. 

Septal  space.  That  portion  of  the  interproximal  space  normally  filled  by  the 
interproximal  gmu  septum,  or  the  septal  tissue. 

Septic.  Pertaining  to  poisonous  matter  produced  by  microorganisms;  espe- 
cially in  connection  with  persistent  pus  formation. 

Septum.  (PI.  Septa.)  A  partition;  that  portion  of  the  alveolar  process  which 
lies  between  the  roots  of  the  teeth  separating  their  alveoli.     See  Gum  Septums. 

Serumal.  Pertaining  to  the  serum  of  the  blood.  Derived  from  serum.  Serumal 
calculus:     Calculus  on  the  roots  of  teeth  derived  from  the  blood. 

Sets  of  line  angles.  First  set:  The  line  angles  formed  by  the  junction  of  the 
surrounding  walls  of  cavities  with  each  other;  as,  buceo-distal  angle,  linguo-gingival 
angle.  See  Figure  4,  Vol.  2.  Second  set:  The  line  angles  formed  by  the  junction 
of  the  surrounding  walls  of  a  cavity  with  (a)  the  pulpal  wall  in  occlusal  cavities; 
as  pulpo-buccal  angle;  (b)  the  axial  wall  in  axial  cavities;  as,  axio-buccal  angle, 
in  a  mesial  or  a  distal  cavity. 

Side  instruments.  Such  instruments  as  may  be  introduced  into  any  regular  set, 
but  which  do  not  follow  the  regular  order  of  the  nomenclature  of  the  other  instru- 
ments in  the  set. 

Sinus.  [L.]  An  opening;  a  hollow;  a  bending.  An  abnormal  opening  from  an 
abnormal  cavity  to  the  surface,  for  the  discharge  of  an  abnormal  secretion.  See 
note  following  definition  of  fistula. 

"In  pathology,  a  narrow  passage  leading  to  an  abscess  or  other  diseased  locality; 
a  fistula."     Century  Dictionary. 

"(Surgery.)  A  long,  narrow,  hollow  tract  leading  from  some  abscess,  etc." 
Dunglison.     Worcester. 

"  (Medical.)  A  narrow,  elongated  cavity,  in  which  pus  is  collected;  an  elongated 
abscess  with  only  a  small  orifice. ' '     Webster. 

"(Surgery.)  Any  long,  narrow  opening  leading  to  an  abscess  or  to  a  diseased 
structure."     Standard  Dictionary. 

' '  A  long,  narrow  pathological  canal  communicating  with  an  abscess  or  a  diseased 
tract. ' '     Foster 's  Medical  Dictionary. 

"An  abnormal  pathway  or  canal,  usually  the  result  of  ulceration."    Gould. 

"Pathologically,  sinus  means  a  narrow  tract  of  variable  length,  leading  from  a 
chronic  abscess  to  a  free  surface. ' '    Quain. 

Smooth-surface  cavity.  A  cavity  formed  by  caries  beginning  in  any  smooth 
surface  of  a  tooth,  or  portion  of  a  surface  free  from  pits  or  fissures.  The  term  is 
confined  to  cavities  beginning  in  the  axial  surfaces  of  the  teeth. 

Specials,  as  applied  to  cutting  instruments.  Such  instruments  as  are  designed 
for  doing  special  things  in  the  preparation  of  cavities,  as  enamel  hatchets,  spoons,  etc. 

Split  teeth.  Teeth  sawed  through  and  the  cut  surfaces  polished  for  showing 
the  penetration  of  caries  of  enamel  and  dentin. 

Spbue.  a  piece  of  wood  or  metal  used  by  a  molder  in  casting  metals,  to  form 
the  ingate  for  the  molten  metal;  used  to  form  the  passage  or  ingate  for  making  an 
inlay  of  cast  metal,  gold,  etc.  Invested  as  attached  to  the  wax  model  of  an  inlay 
and  dravra  out  when  the  investment  is  ' '  set. ' ' 

Sterile.    Not  containing  microorganisms;    aseptic. 

Sterilization.  The  process  of  freeing  a  substance  from  microorganisms  and 
their  spores. 


GLOSSAEY    OF    TECHNICAL.   TERMS    AND    PHRASES.  305 

Sterilize.  To  thoroughly  cleanse;  to  make  an  instrument  or  the  hands  and  nails 
and  tissues  aseptic.  To  remove  absolutely  or  destroy  the  life  of  all  microorganisms 
and  their  spores;    to  make  the  hands  and  instruments  surgically  clean. 

Stomatitis.     Inflammation  of  the  mucous  membranes  of  the  mouth. 

Stomatologt.    The  sum  of  scientific  knowledge  concerning  the  mouth. 

Stopping.    In  England  a  filling  in  a  tooth  is  called  a  stopping. 

Straight  enamel.  Enamel  in  which  the  enamel  rods  lay  parallel  with  each 
other  and  usually  are  straight  from  the  dento-enamel  junction  to  the  aurface  of  the 
enamel.    See  Figure  146,  Vol.  1.    See  Curled  Enamel. 

Stress.  Pres.?ure.  In  dentistry,  the  word  stress  is  applied  to  the  pressure  of 
tilt'  surfaces  of  the  upper  teeth  against  the  lower  as  the  jaws  are  closed  in  niastication. 

Sub-class  name.  A  name  prefixed  to  a  class  name  which  describes  the  form  of 
the  shank  of  an  instrument,  as  binangle  hatchet,  contra -angle  hoe,  etc. 

Subgingival  space.  The  space  between  the  free  margin  of  the  gingivae  and  the 
tooth. 

Sub-order  name.  A  prefix  to  an  order  name  designating  the  manner  or  place 
of  use;    as  mallet  plugger,  hand-plugger,  enamel  hatchet,  etc. 

Subperiosteal  bone.  Bone  lying  xmder  the  periosteum.  Bone  formed  from  the 
periosteum  as  distinguished  from  Haversian  systems  bone. 

Succedaneous  teeth.  The  teeth  which  succeed  to,  or  take  the  places  of  the 
deciduous  teeth  after  the  latter  have  been  shed:     The  incisors,  cuspids  and  bicuspids. 

SuLCATE  GROOVE.    A  groove  following  the  bottom  of  a  sulcus. 

Sulcus.  (PI.  Sulci.)  A  notable  long-shaped  depression  in  the  surface  of  a 
tooth,  the  inclines  of  which  meet  at  an  angle.  A  sulcus  has  a  developmental  groove 
at  the  junction  of  its  inclines. 

Supplemental  groove.  A  shallow  long-shaped  depression  in  the  surface  of  a 
tooth,  generally  with  a  smoothly  rounded  bottom.  Supplemental  grooves  differ  from 
developmental  grooves  in  that  they  do  not  mark  the  junction  of  lobes. 

Supplemental  lobe.  A  lobe  that  does  not  belong  to  the  typical  form  of  the 
tooth ;    an  additional  lobe. 

Supplemental  ridge.  A  ridge  on  the  surface  of  a  tooth  that  does  not  belong 
to  the  typical  form  of  the  tooth;    an  additional  ridge. 

StTPPUKATloN.    The  act  of  pus  formation.    The  formation  of  pus. 

Temporary  teeth.    See  Deciduous  Teeth. 

The  bite.  The  power  of  force  with  which  the  teeth  may  be  closed  in  the  crush- 
ing of  food,  is  called  the  strength  of  the  bite,  or  simply,  the  bite.  It  is  measured 
with  the  gnathodynamometer. 

Thick-necked.  A  tooth  in  which  the  mesio-distal  diameter  of  the  neck  is  nearly 
equal  to  that  of  the  crown.     See  Bell-crowned. 

Note.  The  word  neck  and  the  Latin  word  cervix,  the  neck,  have  had  some  use  in  dentistry 
in  which  cervical  has  been  the  adjective  form.  The  word  cervical  was  used  to  represent  a  constric- 
tion, or  a  supposed  constriction,  between  the  crown  of  a  tooth  and  its  root,  and,  as  used,  its  meaning 
was  much  too  va^e  to  serve  the  purposes  of  modem  dentistry.     Cervical  is  now  practically  obsolete. 

Thirds.  Division  of  a  crown  of  a  tooth ;  as  to  length,  into  occlusal,  or  incisal 
third,  middle  third  and  gingival  third;  as  to  mesio-distal  breadth,  into  mesial  third, 
middle  third,  and  distal  third. 

Tine.  A  tooth,  a  spike,  as  of  a  fork;  a  prong,  as  of  an  antler.  (Webster.)  A 
slender  pointed  instrument;    as  an  exploring  tine. 

Toilet  op  the  cavity.  Consists  in  freeing  the  internal  surfaces  of  the  cavity 
from  all  chips  or  fine  dust.  The  final  cleaning  of  cavity  walls  before  beginning  a 
filling. 

Transverse  ridge.  A  ridge  formed  of  two  triangular  ridges,  which  join  to 
form  a  continuous  ridge  across  the  occlusal  surface  of  a  tooth. 


306  PATHOLOGY    OF    THE    HAKD    TISSUES    OF    THE    TEETH. 

Triangular  ridge.  A  ridge  running  from  the  point  of  a  cusp  toward  the  cen- 
tral portion  of  the  occlusal  surface  of  a  tooth. 

Trypsin.    One  of  the  enzymes.    See  Enzyme. 

Tubercle.  A  slight  rounded  elevation  on  the  surface  of  a  tooth.  Tubercles 
occur  frequently  on  the  linguo-gingival  ridge  of  the  incisors,  and  occasionally  upon 
various  parts  of  other  teeth.    They  are  deviations  from  the  typical  tooth  forms. 

Tubules.  (PI.  Tubuli.)  The  minute  tubular  canals  vt-hieh  radiate  from  the  pulp 
chamber  and  canals  through  the  dentin  to  the  dento-enamel  junction  in  the  crown 
and  to  the  dento-cemental  junction  in  the  root  of  the  tooth. 

Ulitis.  a  general  inflammation  of  the  gums  as  distinguished  from  gingivitus, 
which  is  confined  to  the  free  margins  of  the  gums  and  immediate  neighborhood. 

Viscous  saliva.  Saliva  that  is  noticeably  thick  or  gummy.  Usually  the  saliva 
is  a  very  thin,  watery  fluid,  but  some  persons  have  saliva  that  has  so  large  a  pro- 
portion of  mucus  that  it  is  thick  and  tenacious  to  a  very  noticeable  degree.  See 
Ropy  Saliva. 

Whorls.  Circular  forms  or  segments  of  circular  forms  with  the  form  elements 
arranged  somewhat  after  the  plan  of  the  spokes  of  a  wheel.  Or  form  elements 
arranged  around  a  center. 

Zones  op  injury.  Said  particularly  of  the  injuries  of  the  teeth  in  atrophy. 
These  injuries  are  spread  in  sheets  or  zones  through  certain  parts  of  the  enamel  and 
dentin. 

ZooGLEA.  A  colony  of  microorganisms  imbedded  in  a  viscous  gelatinous  sub- 
stance. 


INDEX  OF  VOLUME   I, 


Abrasion,   treatment   by   filling   of   plati- 
num-gold, "01. 
Abrasive  action  of  food  in  relation  to  be- 
ginning decays  of  enamel,  85,  81). 
Abscess,  lateral,  187. 
Absorbents,  in  drying  cavity  walls,  19l'. 
Absorption   of  interproximal   gum   tissue, 
103,  106. 
results  of,  103,   106. 
Absorption   of  interproximal   gum  tissue 

as  a  result  of  proximal  decays,  101. 
Absorption  of   roots   of   deciduous  teeth, 
127,  238,  239. 
accidents  during,  241. 
variation  in,  240. 
Absorption  of  roots  of  permanent  teeth, 

127. 
Absorption,  process  of,  as  cause  of  ero- 
sion, 49,  54. 
Accidental  exposure  of  pulp  of  first  per- 
manent molar   during   the   childhood 
period,  270. 
Accidents  during  absorption  of  roots  of 
deciduous  teeth,  241. 
delayed    eruption    of    permanent    teeth 

by,  243. 
failure  of  absorption,  241. 
injuries  to  crowns  of  permanent  teeth 

by  abscesses,  243. 
retained  deciduous  cuspids,  245. 
retained  deciduous  molars,  245. 
roots    of    deciduous    molars    remaining 

unabsorbed,  242. 
use  of  X-ray  in  treatment,  246. 
variations  in  the  process  of  absorption, 
244. 
Accretion,  Unes  of,  in  atrophy,  14,  16. 
Acid  as  a  cause  of  erosion,  49,  52. 
Acid  fermentation  and  caries  as  a  result 
of  absorption  of  interproximal  gum 
tissue,  103. 
Acidity  of  the  saliva,  134. 

effect  of  on  dental  caries,  135. 
Alkaline  fluids  as  cause  of  erosion,  49,  55. 
Amalgam  as  a  filling  material,  199. 
Angles    of    teeth    crossed    by    superficial 

spreading  of  caries,  113. 
Antitoxins,  116. 

Apical  ends  of  root  canals  of  the  teeth 
open  during  the  childhood  period,  275. 
Apical  foramina,  completion  of,  260. 
Apical  space,  tenderness  in,  from  diseased 
tooth  pulps,  169. 


Application  of  extension  for   prevention, 

143. 
Area  of  liability,  of  gingival  third  cavi- 
ties, 85,  113,  227. 

of  pro.ximal  cavities,  81,  85,  113,  210. 
Artificial  cleaning  of  the  teeth,  143,  154. 

in  relation  to  superficial  spreading  of 
caries  of  enamel,  89. 

prophylactic  treatment  of  dental  caries, 
188. 
Asepsis  of  mouth  impossible,  158. 
Atrophy  of  the  teeth,  6. 

accretion,  lines  of,  in,  14,  16. 

an  arrest  of  growth,  15. 

Baume,  re,  19. 

blackened  pits  in  incisors  and  cuspids, 
29. 

calcification  of  first  permanent  molars, 
re,  8,  23. 

calcification  of  incisors,  re,  8. 

C  allow 's  case  of  general  deformity  of 
enamel,  32. 

care  in  filling  blackened  pits  in  incisors 
and  cuspids,  29. 

caries  of  incisors  as  result  of,  8. 

caries  of  first  permanent  molars  as  re- 
sult of,  25,  125. 

case  presenting  general  absence  of  ce- 
menting substance  between  enamel 
rods,  35,  36. 

caused  by  eomlition  of  malnutrition, 
11. 

cementing  substance  absent  between 
enamel  rods,  35,  36,  38. 

character  of  injuries  to  teeth,  in,  14,  23. 

color  of  teeth  in,  11. 

danger  of  pulp  exposure  in,  24. 

decay  of  incisors  as  result  of,  8. 

decay  of  first  permanent  molars  as  re- 
sult of,  25. 

definition,  6. 

deformities  of  enamel  other  than,  32. 

dentin  between  enamel  and  pulp  less 
than  normal,  in,  24. 

diagnosis  of,  6,  185. 

discoloration  of  teeth,  on  account  of,  IS 

due  to  malnutrition,  38. 

enamel,  spots  in,  30,  38. 
telescoping  of,  15. 

etiology,  11. 

filling  in  treatment,  25. 

first  permanent  molars,  8,  23. 
frequence  of,  23. 


308 


PATHOLOGY    OF    THE    HARD    TISSUES    OE    THE    TEETH. 


Atrophy  of  the  teeth   (continued). 

general  deformity  of  the  enamel,  32. 

gold  cap  for  first  molars,  27. 

histological  characters  in,  14. 

Hutchinson,  re,  11. 

Hutchinson  teeth,  7,  11. 

illness,  effect  of,  6. 

illustrations  of,  statement  re,  7. 

incisors,  7,  8. 

injury  to  dentin,  17. 

injury  to  enamel,  8,  15. 

interglobular  spaces  in  dentin,  in,  17. 

introduction,  2. 

inverted  finger  nail  deformity,  10. 

lines   of   contemporaneous   calcification 
as  modified  by,  14. 

location  of,  on  the  teeth,  7,  10,  14. 

Magitot,  re,  11. 

malnutrition  as  cause  of,  11. 

measles  as  cause  of,  13. 

modification  of  the  curve  of  the  line  of 
the  dento-enamel  junction  in,  IS. 

observations  of  cases,  12. 

overlapping  of  enamel  in,  15. 

oxyphosphate  of  copper  cement  in   fill- 
ing, 26. 

permanent  fillings  in  first  molars,  28. 

pits  in  the  enamel,  30,  38. 

portion  of  the  teeth  affected  by,  7. 

Prunty's  case,  white  enamel,  35. 

pulps  of,  closer  to  enamel  than  normal, 
29. 

rapid   progress  of  caries  in   atrophied 
first  permanent  molars,  25. 

recurve  of   line  of   dento-enamel  junc- 
tion, 18. 

repair  in  human  teeth,  no  process  of,  (i. 

result  of  measles,  13. 

no  special  disease,  11,  13. 
scarlet  fever,  13. 
syphilis,  7,  11,  13. 
whooping  cough,  13. 

Retzius,  lines  of,  in,  14,  16. 

root,  atrophy  of,  20. 

roots  of  teeth  well  developed  in,  11. 

scarlet  fever  as  cause  of,  13. 

shortening  of  teeth  in,  17. 

Smith 's  case   of  general  deformity  of 
enamel,  34. 

syphilis  as  caiise  of,  7,  11,  13. 

teeth  affected  by,  7. 

telescoping  of  enamel  in.  15. 

temporary  treatment  of  first  molars,  26. 
incisors,  29. 

treatment  of,  25,  28. 

Walkhoff,  re,  19. 

Wedl,  re,  19. 

white  enamel,  35. 

white  spots  in  the  enamel,  34. 

wliooping  cough  as  cause  of,  13. 

Zsigmondy,  re,  19. 
Author's  e.xperiments  re  cause  of  erosion, 
53. 


Author 's  studies  of  hardness  and  softness 

of  teeth,  119. 
general  summary  of  results,  120. 
Author 's   studies  of   the  microorganisms 

of  the  mouth,  138. 
Axial  angles  of  teeth,  immunity  of,   88, 

90. 

Bacillus  alba,  139. 

Backward  decay  of  enamel,  66. 

Baume,  re  atrophy,  19. 

Beginnings  of  dental  caries,  necessity  of 
closer  study  of,  143. 

Bell,  re  dental  caries,  62. 
re  etiology  of  erosion.  50. 

Bicuspid  teeth,  see  Childhood  period  of 
permanent  teeth.  Gingival  third  cavi- 
ties. Pit  and  fissure  cavities,  Proxi- 
mal cavities. 

Bite,  force  of,  161. 
tests  of,  163. 

Bone,  comparison  of  physiological  condi- 
tions of,  with  teeth,  126,  191. 

Brush,  for  the  teeth,  155. 

Brushing  the  teeth,  155. 

Buccal  and  labial  cavities.  See  Gingival 
third  cavities. 

Buccal  and   labial   surfaces,  examination 
of,  181. 
value  of  artificial  cleaning  by  patient, 
189. 

Cacochymic  saliva,  130. 
Calcic  inflammation  of  gums,  186. 
Calcification  of  deciduous  teeth,  238. 
of  first  permanent  molars,  8,  23. 
of  incisors,  8. 
of  permanent  teeth,  258. 
of    permanent    teeth    as    modified    in 
atrophy,  14. 
Calcium  salts  of  dentin  dissolved  out  in 

advance  of  microorganisms,  70. 
Calcium  salts  of  teeth,  no  changes  in,  126, 
191. 
variation  in  amount  in  different  teeth, 
119,  120. 
Callow 's    case    of    general    deformity   of 

enamel,  32. 
Capping  of  pulps  of  first  permanent  mo- 
lars during  childhood  period,  270. 
Care  in  filling  blackened  pits  in  atrophied 

incisors  and  cuspids,  29. 
Care  in  operating,  not  to  arouse  thermal 

sensitiveness,  151. 
Care  of  the  eyes  of  the  dentist,  172,  173. 
Caries  fungus,  139. 
Caries  of  the  teeth,  2,  60. 

abrasive  action  of  food,  in  relation  to 

beginnings  of,  85,  89. 
absor[)tion  of  intorpro.ximal  gum  tissue, 

resulting  in,  103. 
acidity  of  saliva,  effect  of,  135. 
niigles   of   teeth   crossed   by   superficial 
spreading,  113. 


INDEX. 


309 


Caries  of  the  teeth  (continueil). 
angles  of  teeth  iiiimime,  88. 
application  of  extension  for  prevention, 

143. 
areas  of  liabiUty  to,  81,  85,  113,  210, 

227. 
arrest  of,  by  cleaning  by  patient,  182. 
artificial  cleaning  in  relation  to  super- 
ficial spreading,  8S). 
atrophy    of     first     permanent     molars, 

caries  in,  25,  125. 
author's  stutlies  of  hardness  and  soft- 
ness of  teeth,  119. 
axial  angles  of  teeth  generally  immune, 

90.  ' 
backward  decay  of  enamel,  60. 
beginnings  of,  necessity  of  closer  study, 

143. 
Bell,  re,  62. 

buccal  deca3's,  see  Gingival  third  decays. 
calcium    salts    of   dentin,    dissolved    in 

advance  of  microorganisms,  70. 
calcium  salts,  variations  in  amount  of, 

119,  120. 
cause  of,  68. 

cavities,   tenderness  of,  as   a   cause  of 
tenderness     of     peridental     mem- 
brane, 169. 
chemical  theory  of,  63. 
cleaning,  artificial,  re,  89,  143,  154,  182, 

188. 
clinical  features  of,  as  a  whole,  91. 
differences  between  proximal  decays 
in  bicuspids  and  in  molars,  98. 
divorcement  from  pathology,  91. 
gingival  third  decays,  109. 
occlusal   and  proximal  decays  in  bi- 
cuspids, 97. 
occlusal  decays  in  molars,  92. 
pit  and  fissure  decays,  92. 
proximal  decays  in  incisors,  107. 
proximal  decays  in  molars,  93. 
contact,  relation  of  proper  restoration 
of,  to  recurrence  of  decay,  90,  222. 
crowding   of    food   between   the   teeth, 

results  of,  103. 
curative  effect  of  fillings,  193. 
deciduous   incisors   and   cuspids,   treat- 
ment of,  248. 
deciduous  molars,  occlusal  surfaces  of, 
253. 
proximal  surfaces  of,  254. 
definition  of,  65. 

dentin,  caries  of,  66,  68,  74,  91,  142. 
conical  area  of  caries  of,  70. 
disappearance  of  division  walls  of  tu- 
bules, 71. 
enlargement  of  tubules,  71. 
etiology,  68. 

microorganisms  in,  69,  71,  73. 
slowness  of  progress  of,  72. 
swellings  of  tubules,  71. 


dentinal  fibrils,  how  destroyed  by,  148. 
dento-cnamel  junction,  spreading  along, 

69. 
dialysis  of  saliva,  re,  69. 
disease,  a,  of  youth,  117. 
Duddei,  Augustin,  German  translation 

of  Fouchard,  re,  62. 
embrasures,    relation    of    width    of,    to 

proximal  <lecays,  87. 
enamel,  caries  of,  65,  74,  83,  91,  142. 
backward  decay  of,  66. 
beginning  in  pits  and  fissures,  76. 
beginning  in  smooth  surfaces,  80. 
closer  examination  of  injury  to,  83. 
etiology,  68. 

localizations  of  beginnings  of,  74. 
microorganisms  in,  74. 
penetration  of,  in  buccal  and  labial 

surfaces,  90. 
penetration   of,  in  pits  and   fissures, 

76. 
penetration  of,  in  proximal  surfaces, 

77. 
penetration    of,   in   smooth    surfaces, 

77. 
preparation  of  specimens,  83. 
swelling  of  decayed  area,  101. 
enamel,  faults  of,  re,  124. 

fissures  in,  re,  124. 
esthetic  consideration  in  treatment,  232. 
etiology  of,  68. 
examinations  for,  180. 
extension  for  prevention,  application  of, 

143. 
faulty  structure  of  teeth,  re,  124. 
filling,  effect  of,  on  superficial  spread- 
ing, 89. 
first    permanent    molars,    during   child- 
hood period,  265. 
fissures,  decay  in,  124. 
Fouchard,  re,  62. 
Fox,  re,  62. 

fungus,  caries,  cause  of,  73. 
gelatinous  masses  on  the  teeth,  129. 
plaques  in  relation  to  gingival  third 
decays,  111. 
general  statement,  re,  65. 
gingival  third  decays  in  labial  and  buc- 
cal surfaces,  109. 
clinical  features,  109. 
conditions  favoring,  109. 
intermittent  progress  of.  111. 
management  of,  225. 
relation  of  gum  margin  to,  89. 
relation  of  occlusion  to,  85. 
saliva,  effect  of,  favoring  certain  de- 
posits, 111. 
several  teeth  often  attacked,  90. 
glutinous  deposits  from  the  saliva,  136. 
granular  layer  of  Tomes,  re,  69,  125. 
gum  margin,  relation  of,  to  beginning 

decays,  87,  89. 
hardness  of  teeth,  re,  118. 


310 


PATHOLOGY    OF    THE    HARD    TISSUES   OF    THE    TEETH. 


Caries  of  the  teeth  (continued), 
hereditary  predisposition  to,  116. 
conditions  that  influence,  116. 
stronger  in  youth,  117. 
historical,  60. 
Hunter,  John,  re,  62. 
hyaline  area  of  Tomes,  93,  9.5,  108. 
illustrations  of,  statement  re,  70. 
immunity  to,  3,  11-5,  130. 

of  axial  angles  of  teeth,  88,  90. 
changes  in,  118. 
conditions  of,  130. 
recognition  of,  137. 
sulphocyanids  in  saliva,  influence  of, 
131. 
incisor  teeth,  caries  in,  as  a  result  of 

atrophy,  8. 
injuries  to  the  enamel  by,  examination 

of,  83. 
interglobular  spaces   in  dentin,  re,  69, 

125. 
interproximal  gum  tissue,  absorption  of, 

resulting  in,  103. 
interproximal  wear,  resulting  in,  106. 
Koeker,  re,  62. 

labial  decays,  see  Gingival  third  decays. 
lateral  incisors,  lingual  pits  of,  during 

childhood  period,  272. 
Leber  and  Eottenstein,  re,  64. 
lingual  pits  of  lateral  incisors,  during 

childhood  period,  272. 
localization  of  beginnings  of  caries  of 

enamel,  74. 
location  of  nidus  of  each  beginning  of, 

89. 
lodgments  which  do  not  cause,  111. 
Magitot,  re,  64. 

mastication,  cleaning  power  of,  167. 
Michaels,  re,  129. 

microorganisms,  in  caries  of  dentin,  71, 
73. 
in  caries  of  enamel,  74. 
limit  of  superficial  spreading  of,  89. 
Miles  and  Underwood,  re,  64. 
Miller,  W.  D.,  re,  6.5,  71,  91,  142. 
near  approach  of  surfaces  in  relation  to 

form  of  proximal  decays,  86. 
necessity  of  closer  study  of  beginnings 

of,  143. 
New  York  State  Dental  Society,  Com- 
mittee of,  studies  re,  131,  136. 
nidus  of  beginning  of,  89. 
occlusal    surface    decays,    clinical    fea- 
tures, 92. 
importance  of  early  discovery  of,  97. 
in  bicuspids,  97. 
in  molars,  92. 
occlusion,  relation  of,  to,  85. 
oldest  writing  of,  60. 
order  of  occurrence  of  cavities  of  vari- 
ous classes,  203,  208,  216,  225. 
osmosis,  re,  68. 


pain  caused  by,  144. 

pathology  of,  divorcement  from  clinical 

features,  91. 
penetration  of   dentin  by  microorgan- 
isms, 69. 
of  enamel  in  buccal  and  labial  sur- 
faces, 90. 
of  enamel  in  pits  and  fissures,  76. 
of  enamel  in  proximal  surfaces,  77. 
of  enamel  in  smooth  surfaces,  77. 
peridental    membrance,    disease    of    as 

result  of,  103. 
permanent  teeth,  during  childhood  pe- 
riod, 265. 
physical  characters  of  the  teeth,  re,  118. 
physical  examinations  of  the  teeth,  re, 

120. 
pits,  decay  in,  124. 
points  of  beginning  of,  75. 
predisposition  to,  115. 
pregnant  women,  117. 
preparation  of  specimens,  83. 
prevention     of     secondary     extensions 
gingivally  of  proximal  decays,  102. 
principle      governing      beginnings      in 

enamel,  75. 
prophylactic  treatment,  143,  182,  188. 
proximal     surface     decays,     conditions 
which  cause  food  lodgments,  102. 
in  bicuspids,  97. 
in  incisors  and  cuspids,  107. 
in  incisors  during  childhood  period, 

272. 
in  molars,  93. 

misplacement  of  beginnings,  100. 
relation  of  form  of  to  near  approach 

of  surfaces,  86. 
relation  of  gum  margin  to,  87,  89. 
relation  of  occlusion  to,  85. 
progress  in  dentin,  69. 

limited  by  breaking  of  wall  of  cavity, 

72. 
limited  by  dead  pulp  or  discharge  of 

abscess  through  canals,  72. 
limited    by    putrefactive    decomposi- 
tion, 72. 
slowness  of,  72. 
progress  in  enamel,  74. 
rapid  progress  of,  in  atrophy  of  first 

permanent  molars,  25. 
rare  position  of  lingual  decay,  112. 
recession   of  gums,  caries  in  cases  of, 
230. 
treatment  by  filling,  231. 
treatment  with  silver  nitrate,  231. 
recognition  of  susceptibility  and  immu- 
nity to,  137. 
recurrence  of,  relation  of  restoration  of 

proper  contact  to,  90. 
negnard,  re,  63. 

relation  of  form  of  proximal  decays  to 
areas  of  near  approach  of  surfaces, 
86. 


INDEX. 


311 


Caries  of  the  teeth  (continued). 

relation  of  gum  margin  to  beginning 
decays  of  enamel,  87,  8!l. 

relation  of  occlusion  to  beginning  de- 
cays, 85. 

relation   of  proximal   surfaces  to  each 
other,  86. 

relation  of  restoration  of  proper  contact 
to  recurrence  of,  90. 

relation    of    width    of    embrasures    to 
proximal  decay,  87. 

resulting  from  absorption  of  interproxi- 
mal gum  tissue,  103. 

resulting  from  interproximal  wear,  104. 

Robertson,  re,  62. 

ropy  saliva,  effect  on,  136. 

Rose,  re,  131. 

Eottenstein  and  Leber,  re,  64. 

roughening  of  surface  of  decayed  area, 
101,  102. 

saliva,  in  relation  to.  111,  120,  132. 
salts  dialized  from,  69. 

secondary      extensions     gingivally     of 
proximal  decays,  101. 

sensitiveness  caused  by,  144. 

separating   files,   decay   resulting   from 
use  of,  103. 

signs  of  susceptibility  and  immunity  to, 
137. 

silver   nitrate   in   treatment,   231,    248, 
253. 

softness  of  teeth,  re,  118. 

spreading,  along  dento-enamel  junction, 
69. 
around  the  teeth,  113. 
on  proximal  surfaces  of  bicuspids  and 

molars,  81. 
on  smooth  surfaces,  77. 
on  surface  of  enamel,  75. 

staphylococcus,  cause  of,  73. 

streptococcus,  cause  of,  73. 

streptococcus  media,  cause  of,  73. 

studies  of,  3. 
utility  of,  142. 

sugar  dialized  from  a  solution,  69. 

sulphocyanids    in    saliva,   influence    of, 
131. 

superficial    spreading    on    surfaces    of 
teeth,  81,  89,  113. 

surfaces  cleaned  by  friction  of  mastica- 
tion, 85. 

surfaces  not  cleaned  by  friction  of  mas- 
tication, 85. 

susceptibility  to,  115,  130. 
changes  in,  118. 
conditions  of,  130. 
recognition  of,  137. 

swelling  of  decayed  area  of  the  enamel, 
101. 

swellings  of  tubules  in  caries  of  dentin, 
71. 

systemic  conditions,  effects  of,  115,  121. 

technical  procedures  in  treatment  of,  4. 


Tomes,  John,  re,  63. 
treatment  of,  2,  188. 

deciduous  incisors  and  cuspids,  248. 
deciduous  molars,  occlu-sal  surface  de- 
cays of,  253. 
deciduous   molars,   proximal    surface 

decays  of,  254. 
filUngs,  190. 
management   of  cavities   by   classes, 

203. 
prophylactic,    by    artificial    cleaning, 
188. 
Underwood  and  Miles,  re,  64. 
utility  of  studies  of,  142. 
viscosity  of  the  saliva,  re,  136. 
vital  phenomena  in,  144. 
Williams,  J.  Leon,  studies  re,  128. 
zigzag  coccus,  cause  of,  73. 
zodglea  aggregations,  re,  111. 
Cataphoresis,  149. 
Cavities,  classification  of,  203. 
management  of  by  classes,  203. 
first  class,  204. 
second,    third    and    fourth    classes, 

208. 
fifth  class,  225. 
Cavity  walls,  importance  of  dryness  of,  in 

filling,  192. 
Cement,  in  filling  atrophied  first  molars, 
26. 
in  filling  deciduous  teeth,  252,  254. 
in  pulp  capping,  206. 
Cementing     substance,     between     enamel 

rods,  atrophy  of,  35,  36,  38. 
Changes  in  dentin  and  enamel   resulting 

from  early  loss  of  pulp,  148. 
Character  of  injuries  to  teeth  in  atrophv, 

14,  23. 
Chemical  theory  of  dental  caries,  63. 
Chewing  food,  training  in,  to  strengthen 

peridental  membrane,  170. 
Chewing  foods,  force  used  in,  161. 
Childhood  period  of  the  permanent  teeth, 
258. 
caries  during,  265. 
completion  of  apical  foramina,  260. 
eruption  of  the  permanent  teeth,  258. 
growth  of  roots  of  the  permanent  teeth, 

258. 
intercusping  of  the  first  permanent  mo- 
lars, 262. 
lingual  pits  in  lateral  incisors,  272. 
open  apical  ends  of  root  canals  during, 

275. 
pulp  removal  often  bad  practice,  276. 
removal  of  pulps  in   cases   of  delayed 

eruption,  261. 
root  filling,  relation  of  age  of  patient 

to  prognosis,  276. 
special  functions  of  the  first  permanent 

molars,  263. 
suecedaneous  teeth,  259. 
Child  movement,  195. 


312 


PATHOLOGY    OP    THE    HAED    TISSUES    OF    THE    TEETH. 


Children 's  teeth,  absorption  of  roots  of 
deciduous  teeth,  238,  239. 
accidents  during  absorption  of  roots  of 

deciduous  teeth,  241. 
a  word  as  to  handling  of  children,  2.51. 
calcification  of  the  deciduous  teeth,  238. 
cases  which  have  been  neglected  until 

toothache  has  occurred,  256. 
incisors  and  cuspids,  treatment  of  de- 
cays of,  248. 
by  filing  and  silver  nitrate,  248. 
by  temporary  fillings,  252. 
caution  re  use  of  silver  nitrate,  251. 
management  of,  235. 
molars,   treatment   of   occlusal    decays, 
253. 
by  filling,  254. 
by  silver  nitrate,  253. 
molars,  treatment  of  proximal  decays, 
254. 
by  filing,  254. 
by  filling,  255. 
premature  eruptions  of  teeth,  238. 
proximity  of  pulps  of  deciduous  teeth, 

256. 
psychic  influence,  236. 
relation  of  growth  and  shedding  of  the 
deciduous  teeth  to  their  treatment, 
237. 
retained    deciduous   cuspids,   treatment 

of,  245. 
retained  deciduous  molars,  245. 
roots  of  deciduous  teeth  may  be  filled, 

when,  239. 
treatment  of,  247. 
treatment  of  neglected  cases,  256. 
use  of  X-ray  in  treatment,  246. 
Classification  of  cavities,  203. 
Cleaning,  artificial,  prophylactic  treatment 
of  caries,  188. 
by  patient,  in  arresting  caries,  143,  182. 
which  patient  should  do,  154. 
Cleaning  power  of  mastication,  167. 
Cleanliness  of  proximal  surfaces  increased 
by  changes  of  form,  219. 
of  the  teeth,  154. 
Clinical   features   of   dental   caries,   as   a 
whole,  91. 
differences  between  proximal  decays  in 

bicuspids  and  molars,  98. 
divorcement  from  pathology,  91. 
gingival  third  decays,  109. 
occlusal  and  proximal  decays  in  bicus- 
pids, 97. 
occlusal  decays  in  molars,  92. 
pit  and  fissure  decays,  92. 
proximal  decays  in  incisors,  107. 
proximal  decays  in  molars,  93. 
Clinical  thermometer  in  dental  examina- 
tions, 178. 
Color  of  teeth  in  atrophy,  11. 
Comparative    dental   anatomy,    nomencla- 
ture of,  4. 


Composition  of  enamel,  122. 

Composition  of  normal  saliva,  133. 

Contact,  value  of  form  of,  in  proximal 
fillings,  90,  222. 

Crowding  of  food  between  the  teeth,  re- 
sults of,  103. 

Crowns  and  fillings  cut  by  erosion,  47. 

Crowns  in  treatment  of  erosion,  58. 

Crystals  of  saliva,  examinations  of,  130. 

Curative  effect  of  fillings,  193. 

Curled  enamel,  123. 

Cuspid  teeth,  see  Incisor  teeth. 

Darby,  re  etiology  of  erosion,  54. 
Deciduous  teeth,  see  Children  's  teeth. 
Definition  of  atrophy,  6. 

of  dental  caries,  65. 

of  erosion,  39. 
Deformities    of    the    enamel    other    than 

atrophy,  32. 
Dental  caries,  see  Caries. 
Dental  nomenclature,  4. 
Dentin,  amount  between  enamel  and  pulp 
less  than  normal  in  atrophied  teeth, 
24. 

caries  of,  66,  68,  74,  91,  142. 

conical  area  of  caries  in,  70. 

disappearance     of     division     walls     of 
tubules  in  caries  of,  71. 

enlargement  of  tubules  in  caries  of,  71. 

failures  in  development  of,  1. 

hyperesthesia  of,  217. 

injuries  during  development  of,  1. 

injuries  in  atrophy,  17. 

no  change  in,  after  once  formed,  128. 

obtunding  sensitive,  148. 

softened,  filling  over,  205. 
Dentinal  fibrils,  effect  of,  on  integrity  and 
quality  of  dentin  and  enamel,  147. 

how  destroyed  by  caries,  148. 

studies  of,  by  Rose,  146. 
Deposits  on  the  teeth,  129. 
Development  of  enamel  and  dentin,  fail- 
ures in,  1. 

injuries  during,  1. 
Development  of  face,  effect  of  first  per- 
manent molars  on,  263. 
Development  of  teeth,  failure  of,  6. 
Diagno.sis,  178. 

atrophy,  6,  185. 

caries,  180. 

erosion,  40,  185. 

facial  neuralgia,  184. 

food  lodgments,  183. 

gingival  margin,  disease  of,  185. 

hyperemia  of  pulp,  184. 

mucous  membrane,  disease  of,  179. 

paiu,  183. 

thermal      sensitiveness     of     peridental 
membrane,  184. 
Dialysis  of  saliva,  69. 
Discoloration  of  atrophied  teeth,  18. 


INDEX. 


313 


Disease  beginning  at  gum  margin,  as 
cause  of  tenderness  of  peridental 
membrane,  KiS). 

Disease  of  gingival  margin,  diagnosis  of, 
185. 

Disease  of  peridental  membrane  as  a  re- 
sult of  absorption  from  interproxi- 
mal wear,  106. 

Disease  of  peridental  membrane,  etiology, 
169. 

Diseased  glands,  secretion  of,  as  cause  of 
erosion,  49,  .53. 

Diseased  tooth  pulps,  as  cause  of  tender- 
ness of  peridental  membrane,  1(50, 

Dish-shaped  areas  of  erosion,  42. 

Dryness  of  cavity  walls,  importance  of,  in 
filling,  192. 

Duddei,  Augustin,  German  translation  of 
Fouehard,  62. 

Education  of  the  public  by  the  dentist, 

154. 
Embrasures,    relation    of    width    of,    to 

proximal  decays,  87. 
Enamel,  backward  decay  of,  66. 

caries  of,  65,  74,  83,  91,  142. 

composition  of,  122. 

curled,  123. 

deformities  of,  other  than  atrophy,  32. 

difference  in  hardness  and  softness  of, 
122. 

injuries  during  development,   1. 

injuries  to,  in  atrophy,  8,  15. 

no  change  in,  after  once  formed,  128. 

spots  in,  in  atrophy,  30,  38. 

straight,  122. 

telescoping  of,  in  atrophy,  15. 
Enzyme   of  microorganisms   as   cause   of 

erosion,  49,  55. 
Erosion  of  the  teeth,  39. 

absorption,  as  cause  of,  49,  54. 

acid,  as  cause  of,  49,  52. 

alkaline  fluids,  as  cause  of,  49,  55. 

author 's  experiments  re  cause  of,  53. 

Bell,  re  cause  of,  50. 

crowns  and  fillings  cut  by,  47. 

crowns  in  treatment  of,  58. 

Darby,  re  cause  of,  54. 

definition,  39. 

diagnosis,  40. 

diseased  glands,  secretion  of,  as  cause 
of,  49,  53. 

dish-shaped  areas,  42. 

enzyme  of  microorganisms  as  cause  of, 
49,  55. 

etiology,  49. 

faults   in   formation   of  tissues  during 
growth  as  cause  of,  49,  50. 

figured  areas,  46. 

fillings  and  crowns,  cut  by,  47. 

fillings  in  treatment  of,  57. 

final  statement  re  cause  of,  56. 

flattened  areas,  44. 


forms  of,  42. 

Fox,  re  cause  of,  50. 

frequence  of,  41. 

friction  as  cause  of,  49,  50. 

Garretson,  re  cause  of,  50. 

gouty   diathesis,   acid   associated    with, 
as  cause  of,  49,  54. 

Hunter,  .John,  re  cause  of,  50. 

illustrations,  selection  of  cases  for,  48. 

irregular  areas,  46. 

' '  Keilformege  defecte, ' '  43. 

Kirk,  E.  C,  re  cause  of,  54. 

Koch,  C  R.  E.,  re  cause  of,  50,  55. 

Microorganisms  as  cause  of,  49,  55. 

Miller,  W.  D.,  re  cause  of,  51,  52. 

position  of,  39. 

Preiswork,  re  cause  of,  55. 

progress  of,  39. 

proximal  surfaces,  of,  48. 

secretion  of  diseased  glands  as  cause  of, 
49,   53. 

sensitiveness,  treatment  of,  58. 

Tomes,  John,  re  cause  of,  50. 

treatment,  57. 

treatment  of  sensitiveness,  58. 

wedge-shaped  areas,  43. 
Eruption  of  permanent  teeth,  258. 
Eruptions  of  deciduous  teeth,  premature, 

238. 
Esthetic   considerations    in    treatment   of 

caries,  232. 
Etiology  of  atrophy,  11. 

of  caries,  68. 

of  erosion,  49. 
Examinations  of  the  mouth,  178. 
Exposure   and   capping  of   pulp    of   first 

molar  during  childhood  period,  270. 
Extension  for  prevention,  application  of, 
143. 

limitations  of,  214. 

of  gingival  third  cavities,  227. 

of  proximal  cavities,  211. 

of  proximal  cavities  in  incisors  during 
childhood  period,  273. 
Evaporation  in  drying  cavity  walls,  192. 
Eyes  of  the  dentist,  care  of,  172,  173. 

Face,  growth  and  development  of,  effected 
by  first  permanent  molars,  263. 

Facets  produced   by  interproximal  wear, 
10.5. 

Facial  neuralgia,  diagnosis,  184. 

Failure  in  development  of  the  teeth,  1,  6. 

Faults    in    formation    of    tissues    during 
growth  as  a  cause  of  erosion,  49,  50. 

Faults  in  the  structure  of  the  enamel,  124. 

Faulty  structure  of  teeth  not  a  cause  of 
decay,  124. 

Festoons  of  gums,  swellings  of,  185. 

Figured  areas  in  erosion,  46. 

Filing  in  treatment  of  decays  of  decidu- 
ous incisors  and  cuspids,  248. 
molars,  254. 


314 


PATHOLOGY    OF    THE    HAED   TISSUES    OF    THE    TEETH. 


Filling,  effect  of,  on  superficial  spreailing 
of  caries,  89. 
in  eases  of  atrophy,  25. 
in  cases  of  recession  of  gums,  2,31. 
operations,    esthetic    considerations    in, 

232. 
over  softened  dentin,  20.5. 
requirements  in,  to  be  successful,  191. 
Fillings,  cut  by  erosion,  47. 
in  treatment  of  atrophy,  25. 
in  treatment  of  dental  caries,  190. 
curative  effect  of,  193. 
must  be  watertight,  191. 
prophylactic  value  of,  194. 
selection  of  material  for,  198. 
■what  should  be  considered  permanent, 
195. 
in  treatment  of  erosion,  57. 
First  permanent  molars,  atrophy  of,  8,  23. 
caries  of,  during  childhood  period,  265. 
deep  cavities  in,  268. 
exposure  and  capping  of   pulp   during 

childhood  period,  270. 
hyperemia  of  pulp  of,  269. 
importance  of  early  filling  of  pit  and 

fissure  cavities,  268. 
intercusping  of,  262. 
mesial  surface  cavities  in,  271. 
relation  of  depth  of  decay  to  pulp,  267. 
special  functions  of,  263. 
time  of  loss  important,  266. 
Fissure  and  pit  cavities,  clinical  features, 
92,  97. 
conditions  under  which  fillings  should 

not  be  made,  207. 
importance  of  early  treatment,  207. 
in  bicuspids,  206. 
in  molars,  204. 
management  of,  204. 
penetration  of  enamel  in,  76. 
Fissures  in  the  enamel,  124. 

caries  in,  124. 
Flattened  areas  in  erosion,  44. 
Food,   force   required   in   mastication   of, 
165. 
lodgments,  causing  pain  as  a  result  of 

chewing,  183. 
lodgments,  in  the  interproximal  space, 
220. 
Foods,  force  used  in  chewing,  161. 
Foramina,  apical,  completion  of,  260. 
Force  required  in  the  mastication  of  food, 
165. 
used  in  chewing  foods,  161. 
used    in    mastication    in    relation     to 
strength   and  health   of  peridental 
Form  of  decays  of  dentin,  70. 
Form  of  decays  of  dentin,  70. 
of  enamel  beginning  in  pits,  77. 
of   enamel,    beginning   in   smooth    sur- 
faces, 80. 
Forms  of  erosion,  42. 
Fouchard,  re  dental  caries,  62. 


Fox,  re  etiology  of  erosion,  50. 

re  dental  caries,  62. 
Frequence  of  atrophy,  23. 

of  erosion,  41. 
Friction  as  a  cause  of  erosion,  49,  50. 
Functions,  special,  of  the  first  molar,  263. 
Fungus,  caries,  73. 

Garretson,  re  etiology  of  erosion,  50. 
Gelatinous  masses  on  the  teeth,  129. 
Gelatinous  plaques  in  relation  to  gingival 

third  decays.  111. 
General  deformity  of  enamel,  32. 
General  statement  re  dental  caries,  65. 
Gingival   margin,   diseases   of,   diagnosis, 

185. 
Gingival  third  cavities,  area  of  liability, 
85,  113,  227. 
extension  for  prevention,  227. 
in  eases  of  recession  of  gums,  230. 
in  middle  age,  229. 
in  young  persons,  227. 
management  of,  225. 
Gingival  third  decays,  109. 
intermittent  progress  of.  111. 
relation  of  gelatinous  plaques  to,  111. 
relation  of  gum  margin  to,  89. 
relation  of  occlusion  to,  85. 
saliva,   effect  of,   favoring   certain   de- 
posits, 111. 
several  teeth  often  attacked,  90. 
Gingivitis,  simple,  186. 
Glasses  for  the  eyes  of  the  dentist,  173. 
Glossary,  279. 

Glutinous  deposits  from  the  saliva,  136. 
Gnathodynamometer,  records  on,  163. 
Gold  as  a  filling  material,  198. 
Gold   cap   for  atrophied   first  permanent 

molars,  27. 
Gold  fiiUngs,  when  peridental  membranes 

are  abnormally  sensitive,  169. 
Gouty  diathesis,  acid  associated  with,  as 

cause  of  erosion,  49,  54. 
Granular  layer  of  Tomes,  69,  125. 
Growth   and  development  of  face,  effect 

of  first  permanent  molars  on,  263. 
Growth  and  shedding  of  deciduous  teeth 

in  relation  to  their  treatment,  237. 
Growth  of  roots  of  permanent  teeth,  25S. 
Gums,  calcic  inflammation  of,  186. 
recession  of,  caries  in  case  of,  230. 
treatment  by  filling,  231. 
treatment  with  silver  nitrate,  231. 
swellings  of  festoons  of,  185. 
Gutta-percha,  filling  deciduous  teeth,  252. 

Hardness  of  teeth,  118. 

to  cutting  instruments,  122. 
Haversian  systems  in  bone,  126. 
Hereditary  predisposition  to  caries,  116. 

conditions  that  influence,  116. 

stronger  in  youth,  117. 
Hereditary  predisposition  to  disease,  116 


INDEX. 


315 


Historical,  caries  of  the  teeth,  60. 

Hill's  stopping  in  filling  deciduous  teeth, 
252. 

Histological  characters  in  atrophy  of  the 
teeth,  14. 

Howship,  lacunse  of,  127. 

Hunter,  John,  re  denial  naries,  62. 
re  etiology  of  erosion,  50. 

Hutchison,  re  atrophy,  11. 

Hutchinson  teeth,  7,  II. 

Hyaline  area  of  Tomes,  9.^,  n.^,  108. 

Hyper-acid  saliva,  130. 

Hyperemia  of  pulp,  184. 

of  first  permanent  molar  during  child- 
hood period,  269. 

Hyperesthesia  of  dentin,  217. 

Hypersensitiveness  of  peridental  mem- 
branes, 168. 

Hypersensitiveness  to  thermal  changes, 
150. 

Hypertrophy  of  the  gingivae,  186. 

Hypo-acid  saliva,  130. 

Hypoplasia  of  the  teeth,  6. 

Illness,  effect  of,  on  the  development  of 
the  teeth,  6. 

Immunity  to  dental  caries,  3,  115,  130. 
changes  in,  118. 
influence    of    sulphocyanids    in    saliva, 

131. 
of  axial  angles  of  the  teeth,  88,  90. 
recognition  of,  137. 

Imperfect  formation  of  the  teeth,  6. 

Incisor  teeth,  see  Atrophy,  Childhood 
period  of  permanent  teeth,  Children  's 
teeth,  Gingival  third  cavities,  Proxi- 
mal cavities. 

Injuries  by  interproximal  wear,  104. 

Injury  by  use  of  the  tooth  brush,  157. 

Intercusping  of  first  permanent  molars, 
262. 

Interglobular  spaces  in  dentin  in  atrophy, 
17,  24. 
in  caries,  69,  125. 

Interproximal  contact,  value  of  form  of, 
222. 

Interproximal  gum  septum,  health  of. 
222. 

Interproximal  gum  tissue,  absorption  of, 
103,  106. 

Interproximal  space,  food  lodgments  in, 
220. 

Interproximal   wear,   caries   as  result  of, 
106. 
injuries  by,  104. 

Introduction,  1. 

Inverted  finger  nail  deformity  in  atrophy, 
10. 

Irregular  areas  in  erosion,  46. 

Irregularities  caused  by  failure  of  proper 
intercusping  of  first  permanent  mo- 
lars, 262. 


"  Keilformege     defecte "     (wedge-shaped 

defects),  in  erosion,  43. 
Kirk,  E.  C,  re  etiology  of  erosion,  54. 
Koch,  C.  R.  E.,  re  etiology  of  erosion,  50, 

55. 
Kiieker,  re  dental  caries,  62. 

Labial  and  buccal  cavities,  see  Gingival 

third  cavities. 
Labial  and  buccal  surfaces,  examinations 

of,  181. 
value  of  artificial  cleaning  by  patient, 
189. 
Lateral  abscess,  187. 
Lateral  incisors,   lingual  pits   in,   during 

childhood  period,  272. 
I)ulp3    large    compared    with    size    of 
teeth,   276. 
Leber  and  Eottenstein,   re   dental  caries, 

64. 
Leptothrix  buccalis,  140. 
Leptothrix  of  Vignon,  140. 
Ligature,  for  cleaning  the  teeth,  158. 
in  examinations  for  proximal  cavities, 
181. 
Light,  management  of,  172. 
Limitations  of  the  force  of  the  occlusion, 

162. 
Lines  of  accretion  in  atrophy,  14,  16. 
Lines  of  contemporaneous  calcification  of 

the  teeth  as  modified  in  atrophy,  14. 
Lingual   pits   in    lateral   incisors    during 

childhood  period,  272. 
Localizations  of  beginnings  of  caries  in 

enamel,  74. 
Location  of  nidus  of  each  beginning  of 

caries,  89. 
Locations  of  atrophy  on  the  teeth,  7,  10, 

14. 
Lodgments  of  food  in  the  interproximal 

space,  220. 
Lodgments  which  do   not  cause  gingival 

third  decays.  111. 
Loss  of  length  of  arch  by  interproximal 

wear,  104. 

Magitot,  re  atrophy,  11. 

re  dental  caries,  64. 
Malnutrition  as  cause  of  atrophy,  11. 
Management  of  cavities  by  classes,  203. 
Management  of  children 's  teeth,  235. 
Management  of  Ught  in  dental  operations, 

172. 
Management  of  patients,  153. 
Mastication,  cleaning  power  of,  167. 
force  used  in,  161. 

lack  of  proper  and  normal,  as  cause  of 
tenderness  of  peridental  membrane, 
169. 
of  food,  force  required  in,  165. 
Measles  as  a  cause  of  atrophy,  13. 
Mesio-distal  breadth  of  teeth,  importance 
of  restoration  of,  in  filling,  222,  223. 


316 


PATHOLOGY    OF    THE    HARD    TISSUES    OF    THE    TEETH. 


Method  of  preparing  specimens  of  caries, 

83. 
Michaels,  Joseph  P.,  re  sialo-seraeiologv, 

129,  133. 
Micrococcus  irregularis,  140. 

vaginatus,  140. 
Microorganisms,  as  cause  of  erosion.  40, 
55. 
exclusion    of,   does   not   prevent    recur- 
rence of  decay,  191. 
in  caries  of  dentin,  71,  73. 
in  caries  of  enamel,  74. 
limit  of  superficial  spreading   of  colo- 
nies of,  89. 
of  the  mouth,  138. 
Miles  and  Underwood,  re  dental  caries,  C4. 
Miller,  W.  D.,  re  deutal  caries,  65. 
re  etiology  of  erosion,  51,  52. 
re  experiments,  growth  of  microorgan- 
isms of  caries,  71. 
re  investigations  of  dental  caries,  91. 
re  microorganisms  of  mouth,  I.jO, 
re  studies  of  dental  caries,  142. 
re  tooth  powders,  157. 
Misplacement  of  beginning  proximal  de- 
cays, 100. 
Modification  of  the  curve  of  the  line  of 
the  dento-enamel  junction  in  atrophy, 
18. 
Moisture,  removal  of,  from  cavity  walls, 

192. 
Molar  teeth,  see  Atrophy,  Childhood 
period  of  permanent  teeth.  Children  's 
teeth.  First  permanent  molars.  Gingi- 
val third  cavities,  Pit  and  fissure 
cavities,  Proximal  cavities. 
Mouth,  examinations  of,  178. 

not     rendered     aseptic     by     antiseptic 

washes,  158. 
washes,   157. 
Mucous   membranes   of   mouth,   examin.i- 
tion  of,  179. 

Near  approach  of  surfaces  in  relation  to 
form  of  proximal  surface  decays,  86. 

Necessity  of  closer  study  of  beginnings 
of  caries,  143. 

Neuralgia,  facial,  diagnosis,  184. 

New  York  State  Dental  Society,  studies 
of  saliva  by  committee  of,  131,  13G. 

Nidus  of  each  beginning  of  caries,  loca- 
tion of,  89. 

Nomenclature,     of     comparative     dental 
anatomy,  4. 
dental,  4. 

Normal  saliva,  130. 

Numbers  of  species  of  microorganisms  of 
the  mouth,  138. 

Nutrition,  effect  of,  on  the   development 
of  the  teeth,  6. 

Nutritional  changes  in  bone,   126. 

Observations  of  cases  of  atrophy,  12. 
Obtunding  sensitive  dentin,  148. 


Occlusal  surface  cavities,  management  of, 
204. 
clinical  features,  92. 
conditions  under  which   filUngs  should 

not  be  made,  207. 
examination  for,  181. 
importance     of     early     discovery     and 

treatment,  97,  207. 
in  bicuspids,  97,  206. 
in  molars,  92,  207. 
Occlusion,  force  of,  161. 
Occlusion,  relation  of,  to  beginning  decays 

of  enamel,  85. 
Oldest  mention  of  gold   for  filling  teeth, 

61. 
Oldest  writing  of  dental  caries,  60. 
Open  apical  ends  of  root   canals  during 

childhood  period,  275. 
Order  of  occurrence  of  cavities  of  various 

classes,  203,  208,  216,  225. 
Osmosis,  68. 

Overlapping  of  enamel  in  atrophy,  15. 
Oxyphosphate  of  copper  cement  for  filling 
atrophied  first  molars,  26. 
for  filling  children's  teeth,  254. 
Oxyphosphate   of   zinc   as   pulp   capping, 
206. 

Pain  caused  by  dental  caries,  144. 

in  chewing  food,   as   a  result  of  food 

lodgments,  183. 
in  oral  region,  diagnosis,  183. 
Pathology,  divorcement  of,  from  cUnieal 

features  of  caries,  91. 
Patients,  cleaning  of  teeth  by,  154. 
management  of,  153. 
management  of  children,  235. 
Penetration  of  dentin  by  microorganisms, 

69. 
Penetration  of  enamel  in  buccal  and  la- 
bial surfaces,  90. 
in  pits  and  fissures,  76. 
in  proximal  surfaces,  77. 
in  smooth  surfaces,  77. 
Pericementitis,  phagedenic,  186. 
Peridental   membrane,   danger   of   injury 
to,  by  ligatures  around  incisors,  107. 
disease  of,  as  result  of  absorption  of 

interproximal  gum  tissue,  103. 
disease  of,   as  result  of  interproximal 

wear,  106. 
disease  of,  in  relation  to  force  of  bite, 

162. 
hypersensitiveness  of,  168. 
sensitiveness  of,  168. 
strength  and  health   of,  in  relation  to 

force  used  in  mastication,  161. 
tenderness  of,  169. 
tliormal  sensitiveness  of,  184. 
training  in  chewing  food  to  strengthen, 
170. 
Permanence  of  fillings,  conditions  affect- 
ing, 195. 


IKDEX. 


317 


Permanent  fillings,  in  atrophied  first  mo- 
lars, 2H. 
Permanent  fillings,  meaning  of,  1!I5. 
Permanent  teeth,  caries  of,  during  cliiM- 
hood  period,  liGS. 
childhood  period  of,  258. 
delayed  eruption  of,  by  deciduous  teeth, 

•J43. 
injuries  to,  by  abscesses  of  deciduous 
teeth,  243,  244. 
Phagedenic  pericementitis,  186. 
Phagodynamometer,  records  on,  16.5. 
Physical  characters  of  the  teeth,  118. 
Physical  examinations  of  the  mouth,  ITS. 

of  the  teeth,  120. 
Physiological  and  pathological  differences 

between  bone  and  dentin,  126,  191. 
Physiological  conditions  of  teeth  and  bone 

compared,  l!tl. 
Physiological  repair  in  dentin,  no  process 

of,  128. 
Pit  and  fissure  cavities,  clinical  features, 
92,  97. 
conditions  under  which   fillings  should 

not  be  made,  207. 
importance  of  early  treatment,  207. 
in  bicuspids,  206. 
in  molars,  204. 
management  of,  204. 
penetration  of  enamel  in,  76. 
Pits  in  enamel,  124. 
caries  in,  124. 
in  atrophy,  30. 
Photograph,  note  re  use  of  word,  16,  77. 
Photomicrograph,   note    re   use    of   word, 

16,  77. 
Platinum-gold  foil  in  treatment  of  abra- 
sion, 201. 
Points   in   localization   of   beginnings   of 

caries  of  enamel,  75. 
Porcelain  inlay  as  a  filling  material,  201. 
Portion  of  the  teeth  affected  by  atrophy,  7. 
Position  of  erosion,  39. 
Powders  for  the  teeth,  157. 
Predisposition  to  dental  caries,  115. 

to  disease,  115. 
Pregnant  women,  caries  in  teeth  of,  117. 
Preiswerk,  re  etiology  of  erosion,  55. 
Prevention  of  secondary  extension  gingi- 

vally  of  proximal  decays,  102. 
Principle  governing  beginnings  of  caries 

of  enamel,  75. 
Prisms,  use  of,  for  the  eyes,  177. 
Progress  of  caries  in  dentin,  69. 

limited  or  stopped  how,  72. 
Progress  of  caries  of  enamel,  76. 
Progress  of  erosion,  39. 
Prophylactic  treatment  of  caries,  143. 
by  artificial  cleaning,  188. 
by  patient,  182. 
Prophylactic  value  of  fillings,  194. 
of  form  in  proximal  fillings,  222. 
Prophylaxis,  154. 


mastication  as  factor  in,  167. 
Proximal    fillings,    pro[)hylactie    value   of 

form  in,   222. 
Proximal    surface    cavities,    area    of    lia- 
bility, 81,  85,  113,  210. 
conditions  which  cause  food  lodgments, 

102. 
examinations  for,  181. 
extension  for  prevention,  211. 
food  lodgments  in  interproximal  space, 

220. 
form  of  surface  in  relation  to  cleanli- 
ness, 219. 
in   bicuspids   and   molars,   clinical   fea- 
tures, 93,  97. 
importance  of  early  discovery,  98. 
in  highly  susceptible  persons,  215. 
in    incisors    and   cuspids,    clinical    fea- 
tures, 107. 
danger  of  pulp  exposure,  273. 
during  childhood  period,  272. 
importance  of  early  attention  to,  109. 
open  apical  ends  of  root  canals,  275. 
in  middle  age,  217. 
limitation  of  extension  for  prevention, 

214. 
management  of,  208. 
misplacement  of  beginnings,  100. 
prophylactic  value  of  form  in  proximal 
fillings,  222. 
Proximal  surfaces,  erosion  of,  48. 
Pninty  's  case  of  white  enamel,  35. 
Psychic  conditions  in  patients,  153. 
Public,  education  of,  Ijy  the  dentist,  154. 
Pulp,  danger  of  exposure  in  atrophy,  24. 
death   of,   from    thermal    sensitiveness, 

152. 
disease   of,  as   cause  of  tenderness   of 

peridental  membrane,  169. 
hyperemia  of,  184. 

importance  of  early  removal   of,  after 

death   from   thermal   sensitiveness, 

152. 

loss  of,  in  relation  to  force  of  bite,  162. 

of  atrophied  incisors  and  cuspids  closer 

to  incisal  e<lge  than  normal,  29. 
of    deciduous    teeth,    proximity    of,    to 

enamel,  256. 
of  first  permanent  molar,  relation  of  to 
depth   of   decay,   during  childhood 
period,  267. 
capping,     during    childhood    period, 

270. 
hyperemia   of,   during  childhood  pe- 
riod, 269. 
of  incisors,  danger  of  exposure  during 

childhood  period,  273. 
of  upper  lateral  incisors,  274,  276. 
oxyphosphate  of  zinc  capping  for,  206. 
removal  of,  in  cases  of  delayed  erup- 
tion, 261. 
removal  of,  often  bad  practice,  276. 
Pulse,  in  dental  examinations,  178. 


318 


PATHOLOGY    OF    THE    HAKD    TISSUES    OF    THE    TEETH. 


Putrefaction,  141. 

Putrefactive  decomposition  and  disease  of 
peridental  membrane  as  result  of  ab- 
sorption   of   interproximal    gum   tis- 
sue, 103. 
as  result  of  interproximal  wear,  106. 

Pyorrhea  alveolaris,  186. 

Eapidity  of  progress  of  caries  of  dentin, 

72. 
Hare  position  of  lingual  decay  in  a  cuspid, 

112. 
Reaction  of  the  mucus  of  the  mouth,  132. 
Reaction  of  the  saliva,  132. 
Recession  of  gums,   186. 
caries  in  cases  of,  230. 
treatment  by  filling,  231. 
treatment  with  silver  nitrate,  231. 
Recessional  line  of  pulpal  horn,  95. 
Recognition  of  susceptibility  and  immu- 
nity to  dental  caries,  137. 
Recurve  of  line  of  dento-enamel  junction 

in  atrophy,  18. 
Redness,  general,  of  gingivae,  185. 
Regnard,  re  dental  caries,  63. 
Relation  of  form  of  proximal  decays  to 

area  of  near  approach  of  surfaces  of 

the  teeth,  86. 
Relation  of  growth  and  shedding  of  the 

deciduous   teeth   to    their   treatment, 

237. 
Relation  of  gum  margin  to  beginning  of 

decays  of  enamel,  87,  89. 
Relation    of   occlusion   to   localization   of 

caries,  85. 
Relation  of  proximal  surfaces  of  teeth  to 

each  other,  86. 
Relation    of   restoration    of   contact   and 

mesio-distal  breadth  to  recurrence  of 

caries,  90. 
Relation  of  width  of  embrasures  to  proxi- 
mal decays,  87. 
Repair  in  human  teeth,  no  process  of,  6. 
Repair  of  absorptions  of  portions  of  teeth, 

127. 
Results    of    absorption    of   interproximal 

gum  tissue,  103. 
Results  of  interproximal  wear,  104. 
Retained  deciduous  teeth,  245. 
Retzius,  lines  of,  in  atrophy,  14,  16. 
Robertson,  re  dental  caries,  62. 
Root,  atrophy  of,  20. 
Root   canals   of   teeth,   apical   ends   open 

during  childhood  jieriod,  275. 
Root  fillings,  in   deciduous  teeth  may  be 

made  when,  239. 
relation  of  age  of  patients  to  success, 
276. 
Roots  of  permanent  teeth,  growth  of,  258. 
Roots  of  teeth  well  developed  in  atrophy, 

11. 
Ropy  saliva,  135. 
elTect  of,  on  dental  caries,  136. 


Rose,  Carl,  studies  of  dentinal  fibrils,  146. 

studies  of  saliva,  131. 
Eottenstein  and  Leber,  re  dental   caries, 

64. 
Roughening  of  surface  of  decayed  area, 

101,  102. 
Rubber  bands  for  cleaning  teeth,  158. 

SaHva,  132. 

effect    of,    favoring    deposits    on    the 

teeth.  111. 
examination  of  crystals,  130. 
salts  diaUzed  from,  69. 
studies  of,  by  Dr.  Michaels,  129. 
Salts  dialized  from  saliva,  69. 
Scarlet  fever  as  cause  of  atrophy,  13. 
Secondary  extensions  gingivally  of  proxi- 
mal decays,  101. 
Secretion  of  diseased  glands  as  cause  of 

erosion,  49,  53. 
Selection  of  filling  material,  198. 
Self-limiting  diseases,  117. 
Sensation  in  dentin,  146. 
Sensitiveness,  caused  by  dental  caries,  144. 
in  erosion,  40,  58. 
of  normal  dentin,  145. 
of  peridental  membrane,  168. 
thermal,  219. 
Separating  files,  results  of  use  of,  103. 
Shedding  and  growth  of  deciduous  teeth 

in  relation  to  their  treatment,  237. 
Shortening  of  teeth  in  atrophy,  17. 
Sialo-semeiology,  129. 
Signs  of  susceptibility  and  immunity  to 

dental  caries,  137. 
Silver  nitrate,  treatment  of  decays  of  de- 
ciduous incisors  and  cuspids,  248. 
caution  re  use  of,  251. 
treatment  of  caries  in  eases  of  reces- 
sion of  gums,  231. 
treatment  of  occlusal  decays  of  decidu- 
ous molars,  253. 
Simple  gingivitis,  186. 
Slowness  of  progress  of  caries  of  dentin, 

72. 
Smith's    case    of    general    deformity    of 

enamel,  34. 
Smooth    surface    cavities,    see    Gingival 
third    cavities.    Proximal    surface 
cavities. 
Softened  dentin,  filling  over,  205. 
Softness  of  teeth,  118. 

to  cutting  instruments,  122. 
Soft   tissues   of   mouth,   examination   of, 

179. 
Specimens     showing    injury    to    enamel, 

method  of  preparing,  83. 
Spreading  of  dental  caries,  along  dento- 
enamel  junction,  69. 
around  the  teeth,  113. 
on  smooth  surfaces,  77. 
on  surface  of  enamel,  75,  113,  114. 
Staphylococcus,  cause  of  caries,  73. 


INDEX. 


319 


straight  enamel,  122. 
Streptococcus  bucealia,  13!). 
Streptococcus,  cause  of  caries,  73. 
Streptococcus  continuosum,  140. 
Streptococcus  media,  139. 

as  cause  of  caries,  73. 
Subperiosteal  bone,  126. 
Succedaneous  teeth,  259. 
Sugar,  dialized  and  crystallized,  69. 
Sulphocyanids  in  saliva,  influence  of,  131. 
Superficial  spreading  of  caries  around  an- 
gles of  teeth,  1 13. 

effect  of  falling  away  of  enamel  rods 
on,  89. 

on  smooth  surfaces,  77. 

on  surface  of  enamel,  75,  113,  114. 

relation  of  artificial  cleaning  to,  89. 
Surfaces  of  teeth  cleaned  by  mastication, 

85. 
Surfaces  of  teeth  not  cleaned  by  mastica- 
tion, 85. 
Susceptibility  to  dental  caries,  115,  130. 

changes  in,  118. 

influence    of    sulphocyanids    in    saliva, 
131. 

recognition  of,  137. 
Swelling  of  decayed  area  of  enamel,  101. 
Swelling  of  tubules  in  caries  of  dentin,  71. 
Syphilis  as  cause  of  atrophy,  7,  11,  13. 
Systemic      conditions,     affecting     dental 
caries,  115,  121. 

Tape  for  cleaning  teeth,  158. 

Technical  procedures  in  treatment  of 
caries,  4. 

Teeth,   comparison   of  physiological   con- 
ditions of,  with  bone,  191. 
examination  of,  178. 

Telescoping  of  enamel  in  atrophy,  15. 

Temperature,  in  dental  examinations,  178. 

Temporary  teeth,  see  Children  's  teeth. 

Tenderness  of  carious  cavities  cause  of 
tenderness  of  peridental  membrane, 
169. 

Tenderness  of  peridental  membrane, 
causes  of,  169. 

Tests  of  force  of  bite,  163. 

Tetrogenous,  140. 

Thermal  sensitiveness,  150,  219. 
of  peridental  membrane,  184. 

Thermometer,  clinical,  in  dental  examina- 
tions, 178. 

Tomes,  John,  re  dental  caries,  63. 
hyaline  area  of,  93,  95,  108. 
re  etiology  of  erosion,  50. 


Tooth  brush,  injury  by  use  of,  157. 

use  of,  155. 
Tooth  pick,  158. 
Tooth  powders,  157. 
Treatment,  of  atrophied  teeth,  25. 

of  children's  teeth,  235. 

of  erosion,  57. 

of  dental  caries,  188. 

of  interproximal  wear,  105,  106. 

of  sensitive  dentin,  148. 

of  sensitiveness  in  erosion,  58. 

of  tenderness  of  peridental  membrane, 
169. 

of  thermal  sensitiveness,  151. 
Tubules  of  dentin,  disappearance  of  divi- 
sion walls  in  caries,  71. 

Underwood  and  Miles,  re  dental  caries,  64. 
Use  of  teeth  in  relation  to  force  of  bite, 

162. 
Utility  of  studies  of  dental  caries,  142. 

Variations,  as  to  deposits  from  saliva, 
133. 

in  quantity  of  saliva,  131. 

in  salts  of  saliva,  131,  133. 

in  viscosity  of  saliva,  133. 
Viscosity  of  saliva,  135. 

effect  of,  on  dental  caries,  136. 
Vision,  of  the  dentist,  173. 
Vital  phenomena  in  caries,  144. 
Vitality  of  the  teeth,  effect  of,  on  dental 
caries,  144. 

Walkhoff,  re  atrophy,  19. 
Washes,  mouth,  157. 

Water,  removal  of,  from  cavity  walls,  192. 
Wedge-shaped  areas  in  erosion,  43. 
Wedl,  re  atrophy,  19. 
White  enamel,  35. 
White  spots  in  enamel,  34. 
Whooping  cough  as  cause  of  atrophy,  13. 
Williams,  J.  Leon,  studies  re  dental  caries, 
128. 

X-ray,  use  of,  in  treatment  of  deciduous 
teeth,  246. 

Zigzig  coccus,  140. 

as  cause  of  caries,  73. 

Zoogloea  aggregations,  in  relation  to  gin- 
gival third  decays  in  buccal  and  la- 
bial surfaces.  111. 

Zsigmondy,  re  atrophy,  19. 


m 


i'j'l'^'i'.'i'i'. 


i^' 


